From BiblePortal Wikipedia

King James Dictionary [1]

AN'CIENT, a. Usually pronounced most anomalously, ancient. The pronunciation of the first vowel ought to accord with that is antiquity, anger, anchor, &c. Lt. ante, antiquus. We usually apply ancient and old to things subject to gradual decay. We say, an old man, an ancient record but never the old sun, old stars, an old river or mountain.

1. Old that happened or existed in former times, usually at a great distance of time as, ancient authors, ancient days. Old, says Johnson, relates to the duration of the thing itself, as an old coat and ancient to time in general, as an ancient dress. But this distinction is not always observed. We say, in old times, as well as ancient times old customs, &c. In general, however, ancient is opposed to modern, and old to new, fresh or recent. When we speak of a thing that existed formerly, which as ceased to exist, we commonly use ancient, as ancient republics' ancient heroes, and not old republics, old heroes. But when the thing which began or existed in former times, is still in existence, we use either ancient or old as, ancient statues or paintings, or old statues or paintings ancient authors, or old authors, meaning books. But in these examples ancient seems the most correct, or best authorized. Some persons apply ancient to men advanced in years still living but this use is not common in modern practice, though found in scripture.

With the ancient is wisdom. Job.

2. Old that has been of long duration as, an ancient forest an ancient city. 3. Known from ancient times as the ancient continent, opposed to the new continent.

AN'CIENT, n. Generally used in the plural, ancients. Those who lived in former ages, opposed to moderns.

1. In scripture, very old men. Also, governors, rulers, political and ecclesiastical.

The Lord will enter into judgment with the ancients of his people.  Isaiah 3 .  Jeremiah 19 .

God is called the Ancient of days from his eternal existence.  Daniel 7 .

Hooker uses the word for seniors, "They were his ancients," but the use is not authorized.

2. Ancient is also used for a flag or streamer, in a ship of war and for an ensign or the bearer of a flag, as in Shakespeare. Cowel supposed the word, when used for a flag, to be a corruption of end-sheet, a flag at the stern. It is probably the Fr. enseigne.

Ancient demain, in English Law, is a tenure by which all manors belonging to the crown, in the reign of William the Conqueror, were held. The numbers, names &c. of these were all entered in a book called Domes-day Book.

Webster's Dictionary [2]

(1): (a.) Dignified, like an aged man; magisterial; venerable.

(2): (n.) An aged man; a patriarch. Hence: A governor; a ruler; a person of influence.

(3): (n.) An ensign or flag.

(4): (n.) The bearer of a flag; an ensign.

(5): (a.) Old; that has been of long duration; of long standing; of great age; as, an ancient forest; an ancient castle.

(6): (a.) Former; sometime.

(7): (a.) Experienced; versed.

(8): (a.) Known for a long time, or from early times; - opposed to recent or new; as, the ancient continent.

(9): (n.) A senior; an elder; a predecessor.

(10): (n.) One of the senior members of the Inns of Court or of Chancery.

(11): (n.) Those who lived in former ages, as opposed to the moderns.

(12): (a.) Old; that happened or existed in former times, usually at a great distance of time; belonging to times long past; specifically applied to the times before the fall of the Roman empire; - opposed to modern; as, ancient authors, literature, history; ancient days.

International Standard Bible Encyclopedia [3]

ān´shent  : This word renders several Hebrew words: (1) קדם , ḳedhem , which denotes "beforetime," "yore"; generally the remote past (compare  Deuteronomy 33:15 , "ancient mountains";  Judges 5:21 , Kishon, the "ancient river";  Isaiah 19:11 "ancient kings"). (2) זקן , zāḳēn , "old" in years. Whereas the King James Version generally renders the word by "old" (or "elders" when the plural form is found) in six cases "ancient" is used and "ancients" in nine cases. See Ancients . (3) עולם , ‛ōlām , which denotes "long duration" - past or future. In regard to the past it suggests remote antiquity. The connotation may be discovered in such expressions as: "the years of ancient times" ( Psalm 77:5 ); "ancient land-mark" or "paths" ( Proverbs 22:28;  Jeremiah 18:15 ); "ancient people" or "nation" ( Isaiah 44:7;  Jeremiah 5:15 ); "ancient high places" ( Ezekiel 36:2 ). (4) עתּיק , ‛attı̄q ̌ . This word - really Aramaic - comes from a stem which means "to advance," i.e. in age; hence old, aged ( 1 Chronicles 3:22 ). (5) ישׁישׁ , yāshı̄sh , literally, "weak," "impotent," hence decrepit aged; a rare and poetical word, and found only in Job. It is rendered "ancient" only in one instance ( Job 12:12 the King James Version).