A primary particle (adversative or continuative); but, and, etc. -- also, and, but, moreover, now (often unexpressed in English).
1. universally, by way of opposition and distinction; it is added to statements opposed to a preceding statement: ἐάν ὀφθαλμός κτλ. Matthew 6:23; ἐλεύσονται δέ ἡμέραι, Mark 2:20; it opposes persons to persons or things previously mentioned or thought of — either with strong emphasis: ἐγώ δέ, Matthew 5:22, 28, 32, 34, 39, 44; ἡμεῖς δέ, 1 Corinthians 1:23; 2 Corinthians 10:13; σύ δέ, Matthew 6:6; ὑμεῖς δέ, Mark 8:29; οἱ δέ υἱοί τῆς βασιλείας, Matthew 8:12; αἱ ἀλώπεκες ... ὁ δέ υἱός τοῦ ἀνθρώπου Matthew 8:20; Luke 9:58; πᾶς ὁ λαός ... οἱ δέ φαρισαῖοι, Luke 7:29f; ὁ δέ πνευματικός, 1 Corinthians 2:15, and often; — or with a slight discrimination, ὁ δέ, αὐτός δέ: Mark 1:45; Mark 5:34; Mark 6:37; Mark 7:6; Matthew 13:29, 37, 52; Matthew 15:23ff; Luke 4:40, 43; Luke 5:16; Luke 6:8; Luke 8:10, 54; Luke 15:29; οἱ δέ, Matthew 2:5; Mark 3:4; Mark 8:28, etc., etc.; with the addition also of a proper name, as ὁ δέ Ἰησοῦς: Matthew 8:22 (Tdf. omits Ἰησοῦς); 2. μέν ... δέ, see μέν. 3. after negative sentences, but, but rather (German wohlaber): Matthew 6:19f (μή θησαυρίζετε ... θησαυρίζετε δέ); 4. it is joined to terms which are repeated with a certain emphasis, and with such additions as tend to explain and establish them more exactly; in this use of the particle we may supply a suppressed negative clause and give its force in English by inserting I say, and that, so then, etc.): Romans 3:21f (not that common δικαιοσύνη which the Jews boasted of and strove after, but δικαιοσυνεσς ... διά πίστεως); Romans 9:30; 1 Corinthians 2:6 (σοφίαν δέ οὐ τοῦ αἰῶνος τούτου); Galatians 2:2 (I went up, not of my own accord, but etc.); Philippians 2:8; cf. Klotz ad Dev. ii. 2, p. 361f; L. Dindorf in Stephanus Thesaurus ii. col. 928; (cf. Winer's Grammar, 443 (412)). 5. it serves to mark a transition to something new (δέ metabatic); by this use of the particle, the new addition is distinguished from and, as it were, opposed to what goes before: Matthew 1:18; Matthew 2:19; Matthew 10:21; Luke 12:13; Luke 13:1; John 7:14, 37; Acts 6:1; Romans 8:28; 1 Corinthians 7:1; 1 Corinthians 8:1, etc., etc.; so also in the phrase ἐγένετο δέ, see γίνομαι, 2 c. 6. it introduces explanations and separates them from the things to be explained: John 3:19; John 6:39; 1 Corinthians 1:12; 1 Corinthians 7:6, 29; Ephesians 5:32, etc.; — especially remarks and explanations intercalated into the discourse, or added, as it were, by way of appendix: Mark 5:13 (ἦσαν δέ etc. R L brackets); 7. after a parenthesis or an explanation which had led away from the subject under discussion, it serves to take up the discourse again (cf. Winer's Grammar, 443 (412)): Matthew 3:4; Luke 4:1; Romans 5:8; 2 Corinthians 2:12; 2 Corinthians 5:8; 2 Corinthians 10:2; Ephesians 2:4; cf. Klotz ad Devar. ii. 2, p. 376f. 8. it introduces the apodosis and, as it were, opposes it to the protasis: Acts 11:17 R G (1 Macc. 14:29; 2 Macc. 1:34); after a participial construction which has the force of a protasis: Colossians 1:22 (21); cf. Matthiae 2:1470; Kühner, 2:818; (Jelf, § 770); Klotz as above, p. 370f; (Buttmann, 364 (312)). 9. καί ... δέ, but ... also, yea and, moreover also: Matthew 10:18; Matthew 16:18; Luke 2:35 (WH text omits; L Tr brackets δέ); John 6:51; John 15:27; Acts 3:24; Acts 22:29; Romans 11:23; 2 Timothy 3:12; 1 John 1:3; 2 Peter 1:5; cf. Klotz as above, p. 645f; Buttmann, 364 (312); (also Winer's Grammar, 443 (413); Ellicott on 1 Timothy 3:10; Meyer on John 6:51). ἐάν δέ yea even if: John 8:16. 10. δέ never stands as the first word in the sentence, but generally second; and when the words to which it is added cannot be separated, it stands third (as in Matthew 10:11; Matthew 18:25; Mark 4:34; Luke 10:31; Acts 17:6; Acts 28:6; Galatians 3:23; 2 Timothy 3:8, etc.; in οὐ μόνον δέ, Romans 5:3, 11, etc.), or even in the fourth place, Matthew 10:18; John 6:51; John 8:16; 1 John 1:3; 1 Corinthians 4:18; (Luke 22:69 L T Tr WH).