Vine's Expository Dictionary of OT Words 
Nâkar ( נָכַר , Strong'S #5234), “to know, regard, recognize, pay attention to, be acquainted with.” This verb, which is found in both ancient and modern Hebrew, occurs approximately 50 times in the Hebrew Old Testament. The first time is in Gen. 27:23: “… he did not recognize him” (RSV).
The basic meaning of the term is a physical apprehension, whether through sight, touch, or hearing. Darkness sometimes makes recognition impossible (Ruth 3:14). People are often “recognized” by their voices (Judg. 18:3). Nâkar sometimes has the meaning “pay attention to,” a special kind of recognition: “Blessed be the man who took notice of [KJV, “took knowledge of”] you” (Ruth 2:19, RSV).
This verb can mean “to be acquainted with,” a kind of intellectual awareness: “… neither shall his place know him any more” (Job 7:10; cf. Ps. 103:16).
The sense of“to distinguish” is seen in Ezra 3:13: “… The people could not discern the noise of the shout of joy from the noise of the weeping of the people.…”
Yâda‛ ( יָדַע , Strong'S #3045), “to know.” This verb occurs in Ugaritic, Akkadian, Phoenician, Arabic (infrequently), biblical Aramaic, and in Hebrew in all periods. This verb occurs about 1,040 times (995 in Hebrew and 47 in Aramaic) in the Bible. Essentially yâda‛ means: (1) to know by observing and reflecting (thinking), and (2) to know by experiencing. The first sense appears in Gen. 8:11, where Noah “knew” the waters had abated as a result of seeing the freshly picked olive leaf in the dove’s mouth; he “knew” it after observing and thinking about what he had seen. He did not actually see or experience the abatement himself In contrast to this knowing through reflection is the knowing which comes through experience with the senses, by investigation and proving, by reflection and consideration (firsthand knowing). Consequently yâda‛ is used in synonymous parallelism with “hear” (Exod. 3:7), “see” (Gen. 18:21), and “perceive, see” (Job 28:7). Joseph told his brothers that were they to leave one of their number with him in Egypt then he would “know,” by experience, that they were honest men (Gen. 42:33). In the Garden of Eden, Adam and Eve were forbidden to eat of the tree whose fruit if eaten would give them the experience of evil and, therefore, the knowledge of both good and evil. Somewhat characteristically the heart plays an important role in knowing. Because they experienced the sustaining presence of God during the wilderness wandering, the Israelites “knew” in their hearts that God was disciplining or caring for them as a father cares for a son (Deut. 8:5). Such knowing can be hindered by a wrongly disposed heart (Ps. 95:10).
Thirdly, this verb can represent that kind of knowing which one learns and can give back. So Cain said that he did not “know” he was Abel’s keeper (Gen. 4:9), and Abram told Sarai that he “knew” she was a beautiful woman (Gen. 12:11). One can also “know” by being told—in Lev. 5:1 a witness either sees or otherwise “knows” (by being told) pertinent information. In this sense “know” is paralleled by “acknowledge” (Deut. 33:9) and “learn” (Deut. 31:12-13). Thus, little children not yet able to speak do not “know” good and evil (Deut. 1:39); they have not learned it so as to tell another what it is. In other words, their knowledge is not such that they can distinguish between good and evil.
In addition to the essentially cognitive knowing already presented, this verb has a purely experiential side. The “knower” has actual involvement with or in the object of the knowing. So Potiphar was unconcerned about (literally, “did not know about”) what was in his house (Gen. 39:6)—he had no actual contact with it. In Gen. 4:1 Adam’s knowing Eve also refers to direct contact with her—in a sexual relationship. In Gen. 18:19 God says He “knows” Abraham; He cared for him in the sense that He chose him from among other men and saw to it that certain things happened to him. The emphasis is on the fact that God “knew” him intimately and personally. In fact, it is parallel in concept to “sanctified” (cf. Jer. 1:5). A similar use of this word relates to God’s relationship to Israel as a chosen or elect nation (Amos 3:2).
Yâda‛ in the intensive and causative stems is used to express a particular concept of revelation. God did not make Himself known by His name Jehovah to Abraham, Isaac, and Jacob. He did reveal that name to them, that He was the God of the covenant. Nevertheless, the covenant was not fulfilled (they did not possess the Promised Land) until the time of Moses. The statement in Exod. 6:3 implies that now God was going to make Himself known “by His name”; He was going to lead them to possess the land. God makes Himself known through revelatory acts such as bringing judgment on the wicked (Ps. 9:16) and deliverance to His people (Isa. 66:14). He also reveals Himself through the spoken word—for example, by the commands given through Moses (Ezek. 20:11), by promises like those given to David (2 Sam. 7:21). Thus, God reveals Himself in law and promise.
“To know” God is to have an intimate experiential knowledge of Him. So Pharaoh denies that he knows Jehovah (Exod. 5:2) or that he recognizes His authority over him. Positively “to know” God is paralleled to fear Him (1 Kings 8:43), to serve (1 Chron. 28:9), and to trust (Isa. 43:10).
Da‛ath ( דַּעַת , Strong'S #1847), “knowledge.” Several nouns are formed from yâda‛ , and the most frequently occurring is da‛ath which appears 90 times in the Old Testament. One appearance is in Gen. 2:9: “… and the tree of knowledge of good and evil.” The word also appears in Exod. 31:3.
Maddûa‛ ( מַדֻּעַ , Strong'S #4069), “why.” This word, which occurs 72 times, is related to the verb yâda‛ . The word is found in Exod. 1:18: “… Why have ye done this thing, and have saved the men children alive?”
King James Dictionary 
KNOW, no. pret. knew pp. known. L. nosco, cognosco, Gr. although much varied in orthography. Nosco makes novi, which, with g or 100prefixed, gnovi or cnovi, would coincide with know, knew. So L. cresco, crevi, coincides with grow, grew. The radical sense of knowing is generally to take, receive, or hold.
1. To perceive with certainty to understand clearly to have a clear and certain perception of truth, fact, or any thing that actually exists. To know a thing pre
includes all doubt or uncertainty of its existence. We know what we see with our eyes, or perceive by other senses. We know that fire and water are different substances. We know that truth and falsehood express ideas incompatible with each other. We know that a circle is not a square. We do not know the truth of reports, nor can we always know what to believe.
2. To be informed of to be taught. It is not unusual for us to say we know things from information, when we rely on the veracity of the informer. 3. To distinguish as, to know one man from another. We know a fixed star from a planet by its twinkling. 4. To recognize by recollection, remembrance, representation or description. We do not always know a person after a long absence. We sometimes know a man by having seen his portrait, or having heard him described. 5. To be no stranger to to be familiar. This man is well known to us. 6. In scripture, to have sexual commerce with. Genesis 4 . 7. To approve.
The Lord knoweth the way of the righteous. Psalms 1 .
8. To learn. Proverbs 1 . 9. To acknowledge with due respect. 1 Thessalonians 5 . 10. To choose to favor or take an interest in. Amos 3 . 11. To commit to have.
He hath made him to be sin for us, who knew no sin. 2Cor.
12. To have full assurance of to have satisfactory evidence of any thing, though short of certainty.
Webster's Dictionary 
(1): ( v. i.) To be assured; to feel confident.
(2): ( v. i.) To perceive or apprehend clearly and certainly; to understand; to have full information of; as, to know one's duty.
(3): ( v. i.) To be convinced of the truth of; to be fully assured of; as, to know things from information.
(4): ( v. i.) To be acquainted with; to be no stranger to; to be more or less familiar with the person, character, etc., of; to possess experience of; as, to know an author; to know the rules of an organization.
(5): ( v. i.) To recognize; to distinguish; to discern the character of; as, to know a person's face or figure.
(6): ( v. i.) To have sexual commerce with.
(7): ( v. i.) To have knowledge; to have a clear and certain perception; to possess wisdom, instruction, or information; - often with of.
(8): ( n.) Knee.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
(properly יָדִע , Γινώσκω ) is a term used in a variety of senses in the Scriptures. It signifies particularly to understand ( Ruth 3:11), to approve of and delight in ( Psalms 1:6; Romans 8:29), to cherish ( John 10:27), to experience ( Ephesians 3:19). In Job 7:10 it is used of an inanimate object: "He shall return no more to his house, neither shall his place know him any more." By a euphemism it frequently denotes sexual connection ( Genesis 4:1; Matthew 1:25). The other scriptural applications of the word are mostly obvious, as follows:
(1.) It imports to have acquired information respecting a subject.
(2.) It implies discernment, judgment, discretion; the power of discrimination. It may be partial; we see but in part, we know but in part ( 1 Corinthians 13:9).
(3.) It frequently signifies to have ascertained by experiment ( Genesis 22:12).
(4.) It implies discovery, detection; by the law is the knowledge of sin ( Romans 3:20).
Natural knowledge is acquired by the senses, by sight, hearing, feeling, etc.; by reflection; by the proper use of our reasoning powers; by natural genius; dexterity improved by assiduity and cultivation into great skill. So of husbandry (Isaiah 28:36), of art and elegance ( Exodus 35:31), in the instance of Bezaleel. Spiritual knowledge is the gift of God, but may be improved by study, consideration, etc. (See Knowledge).
Particular Phrases.-The priests' lips should keep knowledge ( Malachi 2:7); not keep it to themselves, but keep it in store for ethers; to communicate knowledge is the way to preserve it. Knowledge is spoken of as an emblematical person, as riches, and treasures, as excellency, and as the gift of God ( Proverbs 1:29; Proverbs 8:10, etc.). (See Wisdom). " Knowledge puffeth up, but charity edifieth" ( 1 Corinthians 8:1); i.e. the knowledge of' speculative and useless things, which tend only to gratify curiosity and vanity, which contribute neither to our own salvation nor to our neighbor's, neither to the public good nor to God's glory; such knowledge is much more dangerous than profitable. The true science is that of salvation; the best employment of our knowledge is in sanctifying ourselves, in glorifying God, and in edifying our neighbor: this is the only sound knowledge ( Proverbs 1:7).
God is the source and fountain of knowledge ( 1 Samuel 2:3; 2 Chronicles 1:10; James 1:5). He knows all things, at all times, and in all places. (See Omniscience). Jesus Christ is possessed of universal knowledge; knows the heart of man, and whatever appertains to his mediatorial kingdom ( John 2:24-25; John 16:30; Colossians 2:3). Men know progressively, and ought to follow on to know the Lord ( Hosea 6:3); what we know not now we may know hereafter ( John 13:7). Holy angels know in a manner much superior to man, and occasionally reveal part of their knowledge to him. Unholy angels know many things of which man is ignorant. The great discretion of life and of godliness is to discern what is desirable to be known, and what is best unknown; lest the knowledge of "good lost and evil got," as in the case of our first parents, should prove the lamentable source of innumerable evils ( Genesis 2:9; Genesis 3:7).
Knowledge of God is indispensable, self-knowledge is important, knowledge of others is desirable; to be too knowing in worldly matters is often accessory to sinful knowledge; the knowledge of our Lord Jesus Christ is a mean of escaping the pollutions which are in the world ( John 17:3). Workers of iniquity have no knowledge, no proper conviction of the divine presence ( Psalms 14:4). Some men are brutish in their knowledge ( Jeremiah 51:17); e.g. he who knows that a wooden image is but a shapely-formed stump of a tree, yet worships it; he boasts of his deity, which, infact, is an instance of his want of discernment, degrading even to brutality ( Isaiah 45:20). Some are wicked in their knowledge, "knowing th the depths of Satan, as they speak" ( Revelation 2:20). (See Gnosticism).