By these and other renderings in the A. V. several words in the original are expressed, with no attempt to distinguish them. This may not be always possible in an English version, yet the differences are not unimportant.
γινώσκω, (with its substantive γνῶσις,), ἐπιγινώσκω (with its substantive ἐπίγνωσις), οἶδα and ἐπίσταμαι are the ordinary Greek words. The first two are found together in 1 Cor. 13: in verse 8 these is a knowledge (γωνῶσις) that shall vanish away, for it is explained (ver. 9) "we know (γιν.) in part," so different is this knowledge in its present fragmentary character from what will be "when that which is perfect is come" (ver. 10); which leads to the contrast of ver. 12 "now I know (γιν.) in part, but then shall I fully know (ἐπιγιν.) even as also I am fully known (ἐπιγιν.)." The difference between the two words is the intensive character given to ‘knowledge' γνῶσις (or its verb) by the preposition ἐπί which is added to it, making it ‘a deeper and more intimate knowledge and acquaintance.' Yet only in one passage in the A.V. is this recognized, 2 Cor. 6:9, where ἐπιγινώσκω is rendered ‘well-known.' But the following passages in which the compound ἐπίγνωσις or ἐπιγινώσκω is found will confirm the distinctive force of it: Rom. 3:20; 10:2; Eph. 1:17; 4:13; Phi. 1:9; Col. 1:6, 9, 10; 2:2 ('acknowledgment' A. V.); 3:10; 1 Tim. 2:4; 4:3; Titus 1:1; 2 Pet. 1:2, 3, 8: comp. Matt. 11:27.
In some passages the compound word, specially in the verb, gives the meaning of certain personal knowledge, and the consequent recognition of the truth of a thing, 'recognizing because we know;' see Matt. 7:16, 20; 14:35 ('had knowledge of Him' A. V.); Mark 5:30; 6:33, 54; Luke 1:4, 22 (' perceived ' A. V., so 5:22; Mark 2:8); Luke 24:16, 31; Acts 4:13 ('took knowledge of' A. V. so 24:8); Rom. 1:32; 1 Cor. 14:37 ‘acknowledge' A. V. so 16:18; 2 Cor. 1:13); 2 Cor. 13:5. This may help as to the use of ἐπίγνωσις in such passages as Rom. 1:28 (compare the simple form of the word γνωστός in verse 19 as to how the certain knowledge was to be had); 2 Tim. 2:25; 3:7; Heb. 10:26.
γινώσκω and οἶδα are found together, John 3:10, 11; 8:55; 21:17; Heb. 8:11; 1 John 2:29; 5:19, 20, with the same rendering of the different words used. γινώσκω is ‘to come to know ' and is used of knowledge acquired and communicated objectively, a true apprehension of external impressions; as compared with οἶδα which (from ἰδεῖν ‘to see with the mind's eye') is inward consciousness, knowledge of in one's own mind (hence a derivative of it signifies ‘conscience'); it is the more inclusive term. We read, Heb. 8:11, that there will be no need to say "know (γιν.) the Lord, for all shall know (οἶδα) me" ― of consciousness in oneself, internal knowledge. So 1 John 2:29 "if ye know (οἶδα)" knowledge realized inwardly ― "that he is righteous, ye know (γιν.)" ― have the knowledge from without by witness borne ― "that every one that doeth righteousness is born of him." In chap. 5:20 "we know" is the inwardly realized (οἶδα) as in verses 18, 19, while the second ‘know' is the knowledge we have come to by the Son of God having come. In John 3:10 it was such acquired knowledge (γιν.) as a teacher of Israel ought to have had, while ver. 11 is that of the Lord Jesus and those He associated with Him, "we speak that we do know (οἶδα);" with the same difference at 8:55 ― between the Jews who had no objective knowledge (γιν.) of God, and the knowledge of the Lord (οἶδα three times repeated in the verse). 1 Cor. 8:1: "we know” ― conscious knowledge (οἶδα) that all have knowledge (γν.) ― objective; similarly (γν.) of that which "puffs up." In verse 2 " think that he knoweth" of the ordinary text is οἶδα but ἐγνωκέαι (from γιν.) is better attested, as twice in the last clause ― "he knows nothing," namely objectively, "as he ought to know (γιν.)" ― so ver. 3: in ver. 4 "we know" is inward conscious knowledge (οἶδα), ver. 10 what a man has learned, acquired (γν.)
For οἶδα see Matt. 12:25 (ver. 15 is γνούς ‘having known it'); Mark 1:34: demons had the inward conscious knowledge of who He was. 1 Cor. 2:11 shows its force clearly (note that in the second clause the reading γινώσκω of knowing the things of God seems best attested). Chap. 13:2, know inwardly in my mind (οἶδα), (stronger than if γιν. had been used); 2 Cor. 12 all through. In Eph. 5:5 the true reading ἴστε (from οἶδα) γινώσκοντες brings both words interestingly together ― the objectively acquired knowledge had passed into internal conscious knowledge ― what they were well aware of, knowing ― a process that as to the use of the words could not be reversed. In 2 Tim. 1:15, the apostle had no need to inform Timothy because of conscious knowledge, οἶδα Compare chap. 3:1 where in "this know (γιν.) also" he communicates what could not have been otherwise known. Chap. 1:12 was his own inward realization (οἶδα), as chap. 3:14 was Timothy's (οἶδα).
ἐπίσταμαι is primarily 'to know' with such a knowledge as is gained by proximity to the thing known, being also used for fixing the mind or thoughts on something; it is thus the knowledge gained by experience ― as that of an expert (ἐπιστήμων, an adjective formed from it, found only in Jas. 3:13, is rendered "endued with knowledge"). The verb is found in Mark 14:68 ('understand' A. V.) where it is associated with οἶδα in Peter's denial of the Lord. It occurs often in the Acts, chaps. 18:25; 19:25; 20:18; 26:26; also in Jude 10, there is what they know not (had no conscious knowledge of οἶδα) and know naturally, ἐπίστ. In Acts 19:15 it is found with γινώσκω "Jesus I know, and Paul I am acquainted with (ἐπίστ)." See for the same word 1 Tim. 6:4; Heb. 11:8: Abraham had no knowledge as of experience of where he was going, nor we of what shall be on the morrow. Jas. 4:14.
συνίημι is another word found for ‘understand,' being indeed always so rendered in the A. V. save Mark 6:52 ‘considered' and 2 Cor. 10:12 ‘be wise' (though γινώσκω and οἶδα are also occasionally translated understand ').συνίημι (from σίν and ἶημι) is to bring or set together' (even originally in a hostile sense), it becomes metaphorically the expression of the soul's innate capacity to do so, connecting the outward object with the inward sense; it is to weigh, consider attentively, and so comprehend the meaning of a thing. See Matt. 13:13, 14 and parallel passages, also vers. 19, 23, 51; Mark 7:14; 8:17, 21; Luke 24:45; Acts 7:25. Outside the Gospels and Acts it is only found at Rom. 3:11; 15:21; Eph. 5:17 and 2 Cor. 10:12; in the last text "are not intelligent" would better preserve the sense. The corresponding substantive σύνεσις ‘intelligence' or ‘understanding,' occurs in Eph. 3:4, "my knowledge in the mystery;" Col. 1:9, "spiritual understanding;" also 2:2; 2 Tim. 2:7; and elsewhere, ‘understanding.'