From sun and hiemi (to send); to put together, i.e. (mentally) to comprehend; by implication, to act piously -- consider, understand, be wise.

see GREEK sun

STRONGS NT 4920: συνίημισυνίημι, 2 person plural συνίετε, 3 person plural συνιοῦσιν (Matthew 13:13 R G T; 2 Corinthians 10:12 Rec., from the unused form συνιέω), and συνιᾶσιν (2 Corinthians 10:12 L T Tr WH), and συνιοῦσιν (Matthew 13:13 L Tr WH from the unused (συνιω), subjunctive 3 person plural συνιῶσι (R G L T Tr in Mark 4:12 and Luke 8:10, from the unused συνιέω or from συνίημι) and συνιῶσι (WH in Mark and Luke the passages cited, from the unused συνιω), imperative 2 person plural συνίετε, infinitive συνιέναι, participle συνίων (Romans 3:11 R G T from συιέω), and συνίων (Romans 3:11 L Tr WH, and often in the Sept., from συνιω), and συνίεις (Matthew 13:23 L T Tr WH; Ephesians 5:17 R G; but quite erroneously συνίων, Griesbach in Matthew, the passage cited (Alford on Romans 3:11; cf. WHs Appendix, p. 167; Tdf. Proleg., p. 122); Winers Grammar, 81 (77f); Buttmann, 48 (42); Fritzsche on Rom. vol. i., p. 174f); future συνήσω (Romans 15:21); 1 aorist συνῆκα; 2 aorist subjunctive συνῆτε, συνῶσι, imperative 2 person plural σύνετε (Mark 7:14 L T Tr WH); (σύν, and ἵημι to send);

1. properly, to set or bring together, in a hostile sense, of combatants, Homer, Iliad 1, 8; 7, 210.

2. to put (as it were) the perception with the thing perceived; to set or join together in the mind, i. e. to understand (so from Homer down; the Sept. for בִּין and הִשְׂכִּיל): with an accusative of the thing, Matthew 13:23, 51; Luke 2:50; Luke 18:34; Luke 24:45; followed by ὅτι, Matthew 16:12; Matthew 17:13; followed by an indirect question, Ephesians 5:17; ἐπί τοῖς ἄρτοις, 'on the loaves' as the basis of their reasoning (see ἐπί, B. 2 a. α.), Mark 6:52; where what is understood is evident from the preceding context, Matthew 13:19; Matthew 15:10; Mark 7:14; absolutely, Matthew 13:13-15; Matthew 15:10; Mark 4:12; Mark 8:17, 21; Luke 8:10; Acts 7:25; Acts 28:26; Romans 15:21; 2 Corinthians 10:12; ὁ συνίων or συνίων as a substantive, (Buttmann, 295 (253f); Winers Grammar, 109 (104)), the man of understanding, Hebraistically equivalent to a good and upright-man (as having knowledge of those things which pertain to salvation; see μωρός): Romans 3:11 (from Psalm 13:2 ()). (Synonym: see γινώσκω, at the end.)