From a (as a negative particle) and noieo; not to know (through lack of information or intelligence); by implication, to ignore (through disinclination) -- (be) ignorant(-ly), not know, not understand, unknown.
see GREEK a
see GREEK noieo
a. to be ignorant, not to know: absolutely, 1 Timothy 1:13; τινα, τί, Acts 13:27; Acts 17:23; Romans 10:3; ἐν τίνι (as in Test. Jos. § 14 Fabricii Pseudepigr. ii., p. 717 (but the reading ἠγνόουν ἐπί πᾶσι τούτοις is now given here; see Test. xii. Patr. ad fid. manuscript Cant. etc., Sinker edition, Cambr. 1869)), 2 Peter 2:12, unless one prefer to resolve the expression thus: ἐν τούτοις, ἅ ἀγνοοῦσι βλασφημοῦντες, Winers Grammar, 629 (584) (cf. Buttmann, 287 (246)); followed by ὅτι, Romans 2:4; Romans 6:3; Romans 7:1; 1 Corinthians 14:38 (where the antecedent clause ὅτι κτλ. is to be supplied again); οὐ θέλω ὑμᾶς ἀγνοεῖν, a phrase often used by Paul (an emphatic)scitote: followed by an accusative of the object, Romans 11:25; ὑπέρ τίνος, ὅτι, 2 Corinthians 1:8; περί τίνος, 1 Corinthians 12:1; 1 Thessalonians 4:13; followed by ὅτι, Romans 1:13; 1 Corinthians 10:1; in the passive ἀγνοεῖται 'he is not known' i. e. according to the context 'he is disregarded,' 1 Corinthians 14:38 L T Tr marginal reading WH text; ἀγνωύμενοι (opposed to ἐπιγινωσκόμενοι men unknown, obscure, 2 Corinthians 6:9; ἀγνοούμενος τινι unknown to one, Galatians 1:22; οὐκ ἀγνοεῖν to know very well, τί, 2 Corinthians 2:11 (Wis. 12:10).
b. not to understand: τί, Mark 9:32; Luke 9:45.
c. to err, sin through mistake, spoken mildly of those who are not high-handed or willful transgressors (Sir. 5:15; 2 Macc. 11:31): Hebrews 5:2, on which see Delitzsch.