Bridgeway Bible Dictionary 
Records from the time of Solomon show that the Israelites followed a calendar of twelve months to the year ( 1 Kings 4:7). The successive months, however, do not correspond to the twelve successive months of the calendar used throughout most of the world today.
The Israelite year began with the new moon of mid-spring, which was some time during the second half of March on our calendar. Some of the names that the Israelites originally gave to the various months were changed in later times. The list below contains both old and new names, depending on which is mentioned in the Bible. A common practice was to refer to a month by its number rather than by its name; for example, ‘the fourth month’ rather than ‘Tammuz’ ( 2 Kings 25:3).
The above table follows the calendar used for religious festivals, most of which were regulated according to the new moon and the full moon ( Leviticus 23:6; Leviticus 23:24; Leviticus 23:39; Numbers 28:11). It seems that there was also a secular calendar, which differed from the religious calendar by six months. This meant that the first day of the seventh month of the religious calendar was New Year’s Day on the secular calendar. In everyday speech people often referred to the time of the year not according to the number or name of the month, but according to the festival season ( John 2:13; John 5:1; John 6:4; John 7:2; Acts 2:1; Acts 12:3; Acts 20:6; Acts 20:16; see Feasts ).
Fausset's Bible Dictionary 
Chodesh from Chadash , "new," namely, new moon; Chodesh Yamin "a month of days" ( Genesis 29:14); also the poetical Yerach from Yareach "the moon," so month is connected with moon in European languages; German Mond and Monat ; Greek Meen , Mene ; Latin, Mensis ; Sanskrit, Masa , both "moon" and "month". The interval between the 17th day of the second month ( Genesis 7:11) and the 17th day of the seventh month is said to be 150 days ( Genesis 8:3-4), i.e. five months of 30 days each; thus the year would be 360 days, corresponding to the old Egyptian year, possibly too five days were intercalated to complete the 365 of the solar year; at all events there is an approximation to the solar year. The total duration of the flood was eleven days above a year ( Genesis 7:11; Genesis 8:14), the exact excess of the solar year above the lunar of 354 days. Genesis 1:14; Genesis 1:16 harmonizes with the theory of a double year, solar and lunar.
The Passover depended on the moon, the 14th of Abib coinciding with full moon. The new moon was a regular feast day ( Numbers 10:10; Numbers 28:11-14). Latterly, its appearance (which may be seen 40 hours after the moon's conjunction with the sun) was reported by proper witnesses to the authorities, who announced the month's commencement by twice repeating " Mequdash ," consecrated. Modern Jews observe the lunar month. Its length would be alternately 29 (a "deficient month," Chasar in the Talmud) and 30 days ("full month," Malee' ). The seasons regulated the months, e.g. Abib the first month of the year was that of "ears of grain"; in the Passover in it, on the second day, the sheaf of harvest firstfruits was waved to the Lord ( Leviticus 23:10-12-34-39; Joel 2:28). So the feast of tabernacles in the seventh month celebrated the ingathering of the autumnal fruits; so that a solar year must have regulated the months.
The months were 12 ( 1 Kings 4:7), with an intercalary month every third year, not noticed in the Bible. The modern Jews have seven intercalary months in every 19 years, according to the metonic cycle adopted A.D. 360. Four names of months are mentioned before the Babylonish captivity: Αbib ("the month of ears of grain") made the first month in memory of the Exodus ( Exodus 9:81; Exodus 12:2; Exodus 13:4); Ζif ("the bloom of flowers", or the Assyrian Gay , "bull," the zodiacal Taurus), the second month ( 1 Kings 6:1; 1 Kings 6:37); Βul ("the month of rain"), the eighth month ( 1 Kings 6:38); Εthanim ("the month of gifts", namely, fruits), the seventh ( 1 Kings 8:2). The three latter names are found only in Solomon's reign, when there was much intercourse with Phoenicia; they are probably Phoenician in origin. "Bul" is mentioned on a Sarcophagus found near Sidon in 1855. They are explained by the addition "which is the" second, the eighth, the seventh month.
After the captivity the first month (that of the Passover) was called Νisan ( Nehemiah 2:1); Sivan the third (from the Assyrian Siv "the moon", to whom the Assyrians consecrated it): Esther 8:9. Εlul the sixth ( Nehemiah 6:15); Chisleu the ninth ( Nehemiah 1:1); Τebeth (from the Egyptian Tobi ) the tenth ( Esther 2:16); Sebat the eleventh ( Zechariah 1:7); Αdar the twelfth ( Esther 3:7). The Talmud gives the remaining five: Ιyar the second, Τammuz the fourth (sacred to that idol), Αb the fifth, Τisri the seventh, Μarchesvan (from Mar "to drop") the eighth; mainly named from the Syrian calendar. The intercalary month was Veadar , i.e. the additional Adar. The variations between the lunar and the solar month, each of the lunar ranging over two solar months, prevent exact coincidence with our months. The barley harvest is not until the middle of April, so that Abib or Nisan, in which the Passover first sheaf was offered on the 15th day, coincides with April. Josephus (Ant. 3:10, section 5) says the Passover was while the sun is in Aries, which it does not enter until the end of March. Zif or Iyar is May, Sivan is June, Tammuz is July, Ab is August, Elul is September, Ethanim or Tisri is October, Bul or Marchesvan is November, Chisleu is December, Tebeth is January, Sebat is February, Adar is March.
Hawker's Poor Man's Concordance And Dictionary 
We meet with constant mention in the Bible concerning the months; but it is remarkable, that the Israelites had no particular names for their months until alter their connection, with Egypt. We read in Genesis 7:11 of the second month, when the fountains of the great deep were broken up, and the ark rested on the seventh month upon the mountains of Ararat, ( Genesis 8:4) â€”and the waters decreased continually until the tenth month. After the Exodus took place, and Israel went out of Egypt, we find names first began to be given by the Hebrews to their months, though still numbering them as before. Thus for exampleâ€”"This day came ye out, in the month Abib." ( Exodus 13:4) And so again, ( Deuteronomy 16:1) "Observe the month Abib, (Chodeseh Abib) the Lord thy God brought thee forth out of Egypt by night."But they did not lose sight of their numbering their months, and calling them by their numbers. The children of Israel came into the wilderness of Sin, which is between Elim and Sinai, on the fifteenth day of the second month, after their departing out of the land of Egypt. ( Exodus 16:1. So again, Exodus 19:1) In the third month, when the children of Israel were gone forth out of the land of Egypt, the same day came they unto the wilderness of Sinai. And we find mention of months by numbering through all the Old Testament, and even in the New. (See Numbers 1:1; Ezra 3:8; Jeremiah 36:9; Ezekiel 31:1; Haggai 1:1; Hag 1:15; Zechariah 8:19; Luke 1:26; Luk 1:36)
In Solomon's days we find names more particulary given to their months, yet still preserving the ancient method of speaking of their months after their numbers. Thus 1 Kings 6:1 "And it came to pass, in the four hundred and eighteenth year, after the children of Israel were come out of the land of Egypt, in the fourth year of Solomon's reign over Israel, in the month Zif, which is the second month, that he began to build the house of the Lord." So again, 1 Kings 6:37-38 "in the fourth year was the foundation of the house of the Lord laid, in the month Zif; and in the eleventh year, in the month Bul, which is the eighth month, was the house finished..." So 1 Kings 8:2 Solomon held a feast in the month Ethanim, which is the seventh month. But it was only in the time of Solomon that the months were named, for we do not meet with the mention of the months by names, except that of Abib in Exodus and Deuteronomy, either before or after Solomon, until the Babylonish captivity. But whether the name Abib, which signifies green fruit, or ears of corn, and which was the spring answering to our March, was so particularly called in Egypt, and the Hebrews borrowed the name from thence, or Solomon learnt the names of Zif and Bul from the Phenicians When trading with them, is not easy to determine, neither perhaps is it important to know.
It is probable, however, that the Jews learnt in Babylon, the custom of the Chaldeans, to mark their months as they did by names, and from thence (or the Persians, under whom for a time they dwelt when the monarchy of Babylon was destroyed), they formed the following to all the months in the year.
The names of the months.
1. Nizan, which answers to March.
2. Jiar which answers to April..
3. Sivan which answers to May..
4. Thammuz which answers to June..
5. Ab which answers to July.
6. Elul which answers to August.
7. Tizri which answers to September.
8. Marschevan which answers to October.
9. Casleu which answers to November.
10. Thebet which answers to December.
11. Sebat...which answers to January.
12. Adar. which answers to February.
The Hebrews observed a distinct order in the calculation of their time as it related to holy seasons and ordinary concerns. The holy year, as they termed it, began in the month Nizan, corresponding to our March, called in the Exodus Abib; no doubt, in obedience to that preceptâ€”"This month shall be unto you the beginning of months: it shall be the first month of the year unto you." ( Exodus 12:1-2) The ordinary year for concerns commenced with the Hebrews in the month Tizri, answering to our September.
Smith's Bible Dictionary 
Month. From the time of the institution of the Mosaic law downward, the religious feasts, commencing with the Passover , depended not simply on the month, but on the moon; the 14th of Abib was coincident with the full moon; and the new moons themselves were the occasions of regular festivals. Numbers 10:10; Numbers 28:11-14.
The commencement of the month was generally decided by observation of the new moon. The usual number of months in a year was twelve, as implied in 1 Kings 4:7; 1 Chronicles 27:1-15 , but since twelve lunar months would make, but 354 1/2 days, the years would be short twelve days of the true year, and therefore, it follows as a matter of course that an additional month must have been inserted about every third year, which would bring the number up to thirteen. No notice, however, is taken of this month in the Bible.
In the modern Jewish calendar, the intercalary month is introduced seven times in every nineteen years. The usual method of designating the months was by their numerical order, for example, "the second month," Genesis 7:11, "the fourth month," 2 Kings 25:3, and this was generally retained, even when the names were given, for example, "in the month Zif, which is the second month." 1 Kings 6:1.
The names of the months belong to two distinct periods. In the first place, we have those peculiar to the period of Jewish independence, of which four only, even including Abib , which we hardly regard as a proper name are mentioned, namely,
Zif , the second month, 1 Kings 6:1; 1 Kings 6:37,
Bul , the eighth, 1 Kings 6:38, and
Ethanim , the seventh. 1 Kings 8:2.
In the second place, we have the names which prevailed, subsequent to the Babylonish captivity; of these, the following seven appear in the Bible:
Sivan , the third, Esther 8:9; Baruch 1:8,
Chisleu , the ninth, Nehemiah 1:1; Zechariah 7:1 1 Maccabees 1:54;
Tebeth , the tenth, Esther 2:16;
Sebat , the eleventh, Zechariah 1:7 1 Maccabees 16:14; and
Adar , the twelfth. Esther 3:7; Esther 8:1; 2 Maccabees 15:36.
The names of the remaining five occur in the Talmud and other works; they were,
Tammuz , the fourth,
Ab , the fifth,
Tisri , the seventh, and
Marcheshvan , the eighth.
The name of the intercalary month was
Ve-Adar , that is, the Additional Adar.
The identification of the Jewish months with our own cannot be effected with precision on account of the variations that must inevitably exist between the lunar and the solar month.
Nisan (or Abib) answers to April;
Zif (or Iyar) to May;
Sivan to June;
Tammuz to July;
Ab to August;
Elul to September;
Ethanim (or Tisri) to October;
Bul (or Marcheshvan) to November;
Chisleu to December;
Tebeth to January;
Sebat to February; and
Adar to March.
American Tract Society Bible Dictionary 
The Hebrews months were lunar months, that is, from one new moon to another. These lunar months were each reckoned at twenty-nine days and a half; or rather, one was of thirty days, the following of twenty-nine, and so on alternately: that which had thirty days was called a full or complete month; that which had but twenty-nine days was called incomplete. The new moon was always the beginning of the month and this day they called new-moon day, or new month. The Hebrews usually designated the months only as first, second, etc.; and the names by which they are now known are believed to be of Persian origin, and to have been adopted by the Jews during the captivity. At the exodus from Egypt, which occurred in April, God ordained that that month-the seventh of the civil yearshould be the first of the sacred year, according to which the religious festivals were to be reckoned; and from that time both these modes of numbering the months continued to be employed.
As the Jewish months were governed by the moon, while ours entirely disregard it, the two systems cannot wholly coincide. It is generally agreed, however, that their month Nisan answers most nearly to our April, Iyar to our May, etc.
Twelve lunar months making but three hundred and fifty-four days and six hours, the Jewish year was short of the Roman by twelve days. To recover the equinoctial points, from which this difference of the solar and lunar year would separate the new moon of the first month, the Jews every three years intercalated a thirteenth month, which they called Veadar, the second Adar. By this means their lunar year nearly equaled the solar. See Year .
King James Dictionary 
MONTH, n. L. mensis Gr. a month, from the moon. A space or period of time constituting a division of the year. Month originally signified the time of one revolution of the moon, a lunation, or the period from one change or conjunction of the moon with the sun to another, a period of 27 days, 7 hours, 43 minutes and 5 seconds. This is the periodical month, or as we generally call it, the lunar month. In this sense we still use the word month. But we also apply the term to the space of time in which the sun passes through one sign, or a twelfth part of the zodiac. This period contains 30 days, 10 hours, 29 minutes, 5 seconds, and it called a solar month. In the year, there are twelve solar months, and thirteen lunar months.
In popular language, four weeks are called a month, being nearly the length of the lunar month. A calendar month differs in some degree from a solar month consisting of twenty eight, twenty nine, thirty or thirty one days, as the months stand in calendars or almanacs.
Easton's Bible Dictionary 
1 Kings 4:7 1 Chronicles 27:1-15
"The Hebrews and Phoenicians had no word for month save 'moon,' and only saved their calendar from becoming vague like that of the Moslems by the interpolation of an additional month. There is no evidence at all that they ever used a true solar year such as the Egyptians possessed. The latter had twelve months of thirty days and five epagomenac or odd days.", Palestine Quarterly, January 1889.
Webster's Dictionary 
(n.) One of the twelve portions into which the year is divided; the twelfth part of a year, corresponding nearly to the length of a synodic revolution of the moon, - whence the name. In popular use, a period of four weeks is often called a month.
People's Dictionary of the Bible 
Bibliography Information Rice, Edwin Wilbur, DD. Entry for 'Month'. People's Dictionary of the Bible. https://www.studylight.org/dictionaries/eng/rpd/m/month.html. 1893.
Holman Bible Dictionary 
Hastings' Dictionary of the Bible 
MONTH . See Time.
Hastings' Dictionary of the New Testament 
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
(usually חֹדֶשׁ , Cho'Desh, i.e., New moon; later also יֶרִח , Ye'Rach, Chald. יְרִה , Yerach'; Gr. Μήν , etc.). The terms for ' month" and "moon" have the same close connection in the Hebrew language as in our own and in the Indo-European languages generally; we need only instance the familiar cases of the Greek Μήν and Μήνη , and the Latin Mensis; the German Mond and Amonat; and the Sanscrit Malsa, which answers to both month and moon. The Hebrew Chodesh is perhaps more distinctive than the corresponding terms in other languages; for it expresses not simply the idea of a lunation, but the recurrence of a period commencing definitely with the new moon; it is derived from the word chaddsh, " new," which was transferred in the first instance to the "new moon," and in the second instance to the ' month," or, as it is sometimes more fully expressed, יָמַים
חֹדֶשׁ , "a month of days" ( Genesis 29:14; Numbers 11:20-21; comp. Deuteronomy 21:13; 2 Kings 15:13). The term Yerach is derived from Yareach, "the moon;" it occurs occasionally in the historical ( Exodus 2:2; 1 Kings 6:37-38; 1 Kings 8:2; 2 Kings 15:13), but more frequently in the poetical portions of the Bible.
1. The most important point in connection with the month of the Hebrews is its length, and the mode by which it was calculated. The difficulties attending this inquiry are considerable, in consequence of the scantiness of the Datat. Though it may fairly be presumed from the terms used that the month originally corresponded to a lunation, no reliance can be placed on the mere verbal argument to prove the exact length of the month in historical times. The word appears even in the earliest times to have passed into its secondary sense, as describing a period approaching to a lunation; for in Genesis 7:11; Genesis 8:4, where we first meet with it, equal periods of 30 days are described, the interval between the 17th days of the second and the seventh months being equal to 150 days ( Genesis 7:11; Genesis 8:3-4). We have therefore in this instance an approximation to the solar month, and as, in addition to this, an indication of a double calculation by a solar and a lunar year has been detected in a subsequent date (for from Genesis 8:14, compared with Genesis 7:11, we find that the total duration of the flood exceeded the year by eleven days; in other words, by the precise difference between the lunar year of 354 days and the solar one of 365 days), the passage has attracted considerable attention on the part of certain critics, who have endeavored to deduce from it arguments prejudicial to the originality of the Bible narrative. It has been urged that the Hebrews themselves knew nothing of a solar month, that they must have derived their knowledge of it from more easterly nations (Ewald, Jahrbiich. 1854, page 8), and consequently that the materials for the narrative and the date of its composition must be referred to the period when close intercourse existed between the Hebrews and the Babylonians (Von Bohlen's Introd. to Genesis 2:155 sq.). It is unnecessary for us to discuss in detail the arguments on which these conclusions are founded; we submit in answer to them that the Data are insufficient to form any decided opinion at all on the matter, and that a more obvious explanation of the matter is to be found in the Egyptian system of months. To prove the first of these points, it will be only necessary to state the various calculations founded on this passage: it has been deduced from it (1) that there were 12 months of 30 days each (See Chronology); (2) that there were 12 months of 30 days, with 5 intercalated days at the end to make up the solar year (Ewald, 1.c.); (3) that there were 7 months of 30 days, and 5 of 31 days (Von Bohlen); (4) that there were 5 months of 30 days, and 7 of 29 days (Knobel, in Genesis 8:1-3); or, lastly, it is possible to cut away the foundation of any calculation whatever by assuming that a period might have elapsed between the termination of the 150 days and the 17th day of the 7th month (Ideler, Chronol. 1:70). "The year being lunar, the interval is, in fact, but 148 days; the discrepancy, however, is of no account" (Browne, Ordo Sceclorum, page 326): both extremes are included, as is usual in Hebrew computations. (See Deluge).
But, assuming that the narrative implies equal months of 30 days, and that the date given in 8:14 does involve the fact of a double calcullation by a solar and a lunar year, it is unnecessary to refer to the Babylonians for a solution of the difficulty. The month of 30 days was in use among the Egyptians at a period long anterior to the period of the exodus, and formed the basis of their computation either by an unintercalated year of 360 days or an intercalated one of 365 (Rawlinson's Herodotus, 2:283-286). Indeed, the Bible itself furnishes us with an indication of a double year, solar and lunar, in that it assigns the regulation of its length indifferently to both sun and moon ( Genesis 1:14). (See Year).
From the time of the institution of the Mosaic law downward the month appears to have been a lunar one. The cycle of religious feasts, commencing with the Passover, depended not simply on the month, but on the moon (Josephus, Ant. 3:10, 5); the 14th of Abib was coincident with the full moon (Philo, Vit. Mos. 3, page 686); and the new moons themselves were the occasions of regular festivals ( Numbers 10:10; Numbers 28:11-14). The statements of the Talmudists (Mishna, Rosh Hash. 1-3) are decisive as to the practice in their time, and the lunar month is observed by the modern Jews. The commencement of the month was generally decided by observation of the new moon, which may be detected about forty hours after the period of its conjunction with the sun: in the later times of Jewish history this was effected according to strict rule, the appearance of the new moon being reported by competent witnesses to the local authorities, who then officially announced the commencement of the new month by the twice-repeated word "Mekuddash," i.e., consecrated (see Cudworth's Intellectual System, 2, Append. page 528). According to the rabbinical rule, however, there must at all times have been a little uncertainty beforehand as to the exact day on which the month would begin; for it depended not only on the appearance, but on the announcement: if the important word Mekuddash were not pronounced until after dark, the following day was the first of the month — if before dark, then that day (Rosh Hash. 3:1). But we can hardly suppose that such a strict rule of observation prevailed in early times, nor was it in any way necessary; the recurrence of the new moon can be predicted with considerable accuracy by a calculation of the interval that would elapse either from the last new moon, from the full moon (which can be detected by a practiced eye), or from the disappearance of the waning moon. Hence David announces definitely "To-morrow is the new moon," that being the first of the month ( 1 Samuel 20:5; 1 Samuel 20:24; 1 Samuel 20:27), though the new moon could not as yet have been observed, and still less announced. Jahn (Arch. 3:3, § 352) regards the discrepancy of the dates in 2 Kings 25:27, and Jeremiah 52:31, as originating in the different modes of computing by astronomical calculation and by observation. It is more probable that it arises from a mistake of a copyist, substituting ן for ה , as a similar discrepancy exists in 2 Kings 25:19 and Jeremiah 52:25, without admitting a similar explanation. The length of the month by observation would be alternately 29 and 30 days; nor was it allowed by the Talmudists that a month should fall short of the former or exceed the latter number, whatever might be the state of the weather. The months containing only 29 days were termed in Talmudical language chaser ( חָסֵר ), or "deficient," and those with 30 Nmal ( מָלֵא ), or "full."
The usual number of months in a year was twelve, as implied in 1 Kings 4:7; 1 Chronicles 27:1-15; but inasmuch as the Hebrew months coincided, as we shall presently show, with the seasons, it follows as a matter of course that an additional month must have been inserted about every third year. which would bring the number up to thirteen. No notice, however, is taken of this month in the Bible. We have no reason to think that the intercalary month was inserted according to any exact rule; it was sufficient for practical purposes to add it whenever it was discovered that the barley harvest did not coincide with the ordinary return of the month of Abib. In the modern Jewish calendar the intercalary month is introduced seven times in every 19 years, according to the Metonic cycle, which was adopted by the Jews about A.D. 360 (Prideaux's Connection, 1:209, note). At the same time the length of the synodical month was fixed by R. Hillel at 29 days, 12 hours, 44 minutes, and 3 ½ seconds, which accords very nearly with the truth.
2. The usual method of designating the months was by their numerical order, e.g. "the second month" ( Genesis 7:11), "the fourth month" ( 2 Kings 25:3); and this was generally retained even when the names were given, e.g. "in the month Zif, which is the second month" ( 1 Kings 6:1); "' in the third month, that is, the month Sivan" ( Esther 8:9). An exception occurs, however, in regard to Abib in the early portion of the Bible ( Exodus 13:4; Exodus 23:15; Deuteronomy 16:1), which is always mentioned, by name alone, inasmuch as it was necessarily coincident with a certain season, while the numerical order might have changed from year to year. We doubt indeed whether Abib was really a proper name. In the first place, it is always accompanied by the article, "the Abib," as an appellation (the season of the new ears of grain); in the second place, it appears almost impossible that it could have been superseded by Nisan if it had been regarded as a proper name, considering the important associations connected with it. The practice of the writers of the post-Babylonian period in this respect varied: Ezra, Esther, and Zechariah specify both the names and the numbered order; Nehemiah only the former; Daniel and Haggai only the latter.
The names of the months belong to two distinct periods: in the first place we have those peculiar to the period of Jewish independence, of which four only, even including Abib, which we hardly regard as a proper name, are mentioned, viz.: Abib, in which the Passover fell ( Exodus 13:4; Exodus 23:15; Exodus 34:18; Deuteronomy 16:1), and which was established as the first month in commemoration of the exodus ( Exodus 12:2); Zif, the second month ( 1 Kings 6:1; 1 Kings 6:37); Bul, the eighth ( 1 Kings 6:38); and Ethanim, the seventh ( 1 Kings 8:2) — the three latter being noticed only in connection with the building and dedication of the Temple, so that we might almost infer that their use was restricted to the official documents of the day, and that they never attained the popular use which the later names had. Hence it is not difficult to account for their having been superseded. In the second place we have the names which prevailed subsequently to the Babylonian captivity; of these the following seven appear in the Bible: Nisan, the first, in which the Passover was held ( Nehemiah 2:1; Esther 3:7); Sivan, the third ( Esther 8:9; Baruch 1:8); Elul, the sixth ( Nehemiah 6:15; 1 Maccabees 14:27); Chisleu, the ninth ( Nehemiah 1:1; Zechariah 7:1; 1 Maccabees 1:54); Tebeth, the tenth ( Esther 2:16); Sebat, the eleventh ( Zechariah 1:7; 1 Maccabees 16:14); and Adar, the twelfth ( Esther 3:7; Esther 8:12; 2 Maccabees 15:36). The names of the remaining five occur in the Talmud and other works; they were Iyar, the second (Targum, 2 Chronicles 30:2); Tammuz, the fourth (Mishna, Taan. 4: 5); Ab, the fifth, and Tisri, the seventh (Rosh Hash. i, 3); and Marchesvan, the eighth (Taan. 1:3; Josephus, Ant. 1:3, 3). The name of the intercalary month was Veadar, i.e., the additional Adar, because placed in the calendar after Adar and before Nisan. The opinion of Ideler (Chronol. 1:539) that the first Adar was regarded as the intercalary month, because the feast of Purim was held in Veadar in the intercalary year, has little foundation.
The first of these series of names is of Hebrew origin, and has reference to the characteristics of the seasons circumstance which clearly shows that the months returned at the same period of the year; in other words, that the Jewish year was a solar one. Thus Abib ( אבַיב ) was the month of" ears of corn," Zif the month of "blossom" ( זַו or זַיו , or, more fully, as in the Targum, זַיו נַצָּנִיָּא , "the bloom of flowers;" another explanation is given in Rawlinson's Herodotus, 1:622; viz. that Ziv is the same as the Assyrian Giv, "bull," and answers to the zodiacal sign of Taurus), and Bul the month of "rain" ( בּוּל ; the name occurs in a recently discovered Phoenician inscription [Ewald, Jathrb. 1856, page 135]. A cognate term, מִבּוּל , is used for the "deliuge" [ Genesis 6:17, etc.]; but there is no ground for the inference drawn by Von Bohlen [Introd. to Genesis 2:156] that there is any allusion to the month Bul). With regard to Ethanim there may be some doubt, as the usual explanation, "the month of violent or, rather, Incessant rain," is decidedly inappropriate to the seventh month. Thenius, on 1 Kings 8:2, suggests that the true name was אתנים , as in the Sept. Ἀθανίμ , and that its meaning was the " month of gifts," i.e., of fruit, from תָּנָה , "to give." There is the same peculiarity in this as in Abib. viz. the addition of the definite article ( הָאֵיתָנַים ).
In the second series, both the origin and the meaning of the terms are controverted. It was the opinion of the Talmudists that the names were introduced by the Jews who returned from the Babylonian captivity (Jerusalem Talmud, Rosh Hash. 1:1), and they are certainly used exclusively by writers of the post-Babylonian period (see Benfey and Stern, Monatsnamen Einiger Alter Vuolker, Berlin, 1836). It was therefore perhaps natural to seek for their origin in the Persian language, and this was done some years since by Benfey (Monatsnamen) in a manner more ingenious than satisfactory. The view, though accepted to a certain extent by Gesenius in his Thesaurus, has since been abandoned, both on philological grounds and because it meets with no confirmation from the monumental documents of ancient Persia. The names of the months, as read on the Behistun inscriptions, Garmapada, Bagtayadish, Atriyata, etc., bear no resemblance to the Hebrew names (Rawlinson's Herodotus, 2:593-6). The names are probably borrowed from the Syrians, in whose regular calendar we find names answering to Tisri, Sebat, Adar, Nisan, Iyar, Tammuz, Ab, and Elul (Ideler, Chronol. 1:430). The names of the Syrian months appear to have been in many instances of local use: for instance, the calendar of Heliopolis contains the names of Ag and Gelon (Ideler, 1:440), which do not appear in the regular Syrian calendar, while that of Palmyra, again, contains names unknown to either. Chisleu and Tebeth appear on the Palmyrene inscriptions (Gesenius, Thesaur. pages 702, 543). The resemblance in sound between Tebeth and the Egyptian Tobi, as well as its correspondence in the order of the months, was noticed by Jerome (ad Ezekiel 39:1). Sivan may be borrowed from the Assyrials, who appear to have had a month so named, sacred to Sill or the moon (Rawlinson,1:615). Marchesvan, coinciding as it did with the rainy season in Palestine, was probably a purely Hebrew term. Von Bohlen connects it with the root rachdsh ( רָחִשׁ ), "to boil over" (Introd. To Genesis 2:157). The modern Jews consider it a compound word, Mar, "drop," and Cheshvan, the former betokening that it was wet, and the latter being the proper name of the month (De Sola's Mishna, page 168, note). With regard to the meaning of the Syrian names we can only conjecture from the case of Tammuz, which undoubtedly refers to the festival of the deity of that name mentioned in Ezekiel 8:14, that some of them may have been derived from the names of deities. We draw attention to the similarity between Elul and the Arabic name of Venus Urania, Alil-At (Herod. 3:8); and again between Adar, the Egyptian Athor, and the Syrian Atargatis. Hebrew roots are suggested by Gesenius for others, but without much confidence. The Hebrew forms of the names are: נַיסָן , אַיָּר , סַיוָן , תִּמּוּז , אָב , אלֵוּל , תַּשְׁרַו , מִרְחֶשְׁוָן , כַּסְלֵו , טֵבֵת , שְׁבָט , אֲדָר , and וְאָדָר .
Subsequently to the establishment of the Syro-Macedonian empire, the use of the Macedonian calendar was gradually adopted for the purpose of literature or intercommunication with other countries. Josephus, for instance, constantly uses the Macedonian months, even where he gives the Hebrew names (e.g. in Ant. 1:3, 3, he identifies Marchesvan with Dius, and Nisan with Xanthicus, and in 7:7, 6, Chisleu with Appelleus). The only instance in which the Macedonian names appear in the Bible is in 2 Maccabees 11:30; 2 Maccabees 11:33; 2 Maccabees 11:38, where we have notice of Xanthicus in combination with another named Dioscorinthius ( 2 Maccabees 11:21), which does not appear in the Macedonian calendar. Various explanations have been offered with respect to the latter. Any attempt to connect it with the Macedonian Dius fails on account of the interval being too long to suit the narrative, Dius being the first and Xanthicus the sixth month. The opinion of Scaliger (Emend. Temp. 2:94) that it was the Macedonian intercalary month rests on no foundation whatever, and Ideler's assumption that that intercalary month preceded Xanthicus must be rejected along with it (Chronol. 1:399). It is most probable that the author of 2 Macc. or a copyist was familiar with the Cretan calendar, which contained a month named Dioscurus, holding the same place in the calendar as the Macedonian Dystrus (Ideler, 1:426), i.e., immediately before Xanthicus, and that he substituted one for the other. This view derives some confirmation from the Vulgate rendering, Dioscorus. We have further to notice the reference to the Egyptian calendar in 3 Maccabees 6:38, Pachon and Epiphi in that passage answering to Pachons and Epep, the ninth and eleventh months (Wilkinson, Anc. Egyp. 1:14, 2d ser.).
3. The identification of the Jewish months with our own cannot be effected with precision on account of the variations that must inevitably exist between the lunar and the solar month, each of the former ranging over portions of two of the latter. It must therefore be understood that the following remarks apply to the general identity on an average of years. As the Jews still retain the names Nisan, etc., it may appear at first sight needless to do more than refer the reader to a modern almanac, and this would have been the case if it were not evident that the modern Nisan does not correspond to the ancient one. We are indebted to J.D. Michaelis for discovering the true state of this case, after the rabbinical writers had so universally established an erroneous opinion that it has not even yet disappeared from our popular books. His dissertation, "De Mensibus Hebraeorum" (in his Commentationes Per Annos 1763-68 Oblatae [Bremen, 1769], page 16; translated by W. Bowyer, Lond. 1773; also in the Critica Biblica [London, 1827], 3:324-340), proceeds on the following chief arguments: First, that if the first month began with the new moon of March, as was commonly asserted, the climate of Palestine would not in that month permit the oblation of the sheaf of barley, which is ordered on the second day of the Paschal Feast ( Leviticus 23:10); nor could the harvest be finished before the Feast of Weeks, which would then fall in May; nor could the Feast of Tabernacles, which was after the gathering of all fruits, accord with the month of September, because all these feasts depend on certain stages in the agricultural year, which, as he shows from the observations of travellers, solely coincide with the states of vegetation which are found, in that climate, in the months of April, June, and October. This has been confirmed by later accounts; for the barley harvest does not take place even in the warm district about Jericho till the middle of April, and in the upland districts not before the end of that month (Robinson's Researches, 1:551; 3:102, 145).
Secondly, that the Syrian calendar, which has essentially the same names for the months, makes its Nisan absolutely parallel with our April. Lastly, that Josephus (Ant. 2:14, 6) synchronizes Nisan with the Egyptian Pharmuth, which commenced on the 27th of March (Wilkinson, 1.c.), and with the Macedonian Xanthicus, which answers generally to the early part of April, though considerable variation occurs in the local calendars as to its place (comp. Ideler, 1:435, 442). He further informs us (3:10, 5) that the Passover took place when the sun was in Aries, which it does not enter until near the end of March. Michaelis concludes that the later Jews fell into this departure from their ancient order either through some mistake in the intercalation, or because they wished to imitate the Romans, whose year began in March. Ideler says, "So much is certain, that in the time of Moses the month of ears cannot have commenced before the first days of our April, which was then the period of the vernal equinox" (Handbuch der Chronologie, 1:490). As Nisan, then, began with the new moon of April, we have a scale for fixing the commencement of all the other months with reference to our calendar; and we must accordingly date their commencement one whole month later than is commonly done: allowing, of course, for the circumstance that, as the new moon varies in its place in our solar months, the Jewish months will almost invariably consist of portions of two of ours. For the details of each month, (See Jewish Calendar). See, in addition to the treatises above noticed, Langenberg, De Mense Ve. Terun Hebrceorum Lunari (Jen. 1713). (See Chronology).
International Standard Bible Encyclopedia 
munth ( חדש , ḥōdhesh , ירח , yeraḥ ; μήν , mḗn ): Ḥōdhesh is strictly the "new moon," the appearance of which marked the beginning of the month, commonly indicated by rō'sh ha - ḥōdhesh . Yeraḥ is derived from yārēaḥ , "moon," which comes from the verb that means "to wander," "to make a circuit." Thus the month was lunar, the period of the moon's circuit. The Greek mēn also meant "moon," from the Sanskrit ma , "to measure," the Latin mensis and our "moon" being derived from the same root. See Calendar; Time; Astronomy .
Ḥōdhesh , or rather rō'sh ha - ḥōdhesh , was observed as a festival ( 1 Samuel 20:5 , 1 Samuel 20:18 , 1 Samuel 20:24; Isaiah 1:14 ).
- Month from Bridgeway Bible Dictionary
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- Month from International Standard Bible Encyclopedia