From eucharistos; to be grateful, i.e. (actively) to express gratitude (towards); specially, to say grace at a meal -- (give) thank(-ful, -s).

see GREEK eucharistos

1. to be grateful, feel thankful; so in the decree of the Byzantines in Demosthenes pro cor., p. 257, 2.

2. to give thanks (so Posid. quoted in Athen. 5, p. 213 e.; Polybius, Diodorus, Philo, Josephus, Plutarch, Epictetus, others; cf. Lob. ad Phryn., p. 18 (Winer's Grammar, 23 (22))): τίνι, especially τῷ Θεῷ, Luke 17:16; Acts 27:35; Acts 28:15; Romans 14:6; Romans 16:4; 1 Corinthians 14:18 (see below); Philippians 1:3; Colossians 1:3, 12; Philemon 1:4; (with the accusative (hence, as the nominative) in the passive, ἵνα ... ὑπέρ τῶν ἀγαθῶν ὁ Θεός ἐυχαρίστηται, Philo, quis rer. div. her. § 36). simply, so that τῷ Θεῷ must be added mentally: Romans 1:21; (1 Corinthians 14:17); 1 Thessalonians 5:18; especially where the giving of thanks customary at the beginning of a feast, or in general before eating, is spoken of: Matthew 15:30; Matthew 26:27; Mark 8:6; Mark 14:23; Luke 22:17, 19; John 6:11, 23; 1 Corinthians 11:24; εὐχαριστεῖν τῷ Θεῷ διά Ἰησοῦ Χριστοῦ, through Christ i. e. by Christ's help (because both the favors for which thanks are given and the gratitude which prompts the thanks are due to Christ (cf. Winer's Grammar, 378 (354) note)): Romans 1:8; Romans 7:2.) R WH marginal reading; Colossians 3:17; τῷ Θεῷ ἐν ὀνόματι Χριστοῦ (see ὄνομα, 2 c.), Ephesians 5:20. Of that for or on account of which thanks are given to God, we find — περί τίνος, the genitive of person, concerning, with regard to one (1 Thessalonians 1:2); 2 Thessalonians 1:3 (cf. Ellicott, in the place cited); with ὅτι added epexegetically, Romans 1:8 (where R G ὑπέρ); 2 Thessalonians 2:13; with addition of ἐπί and the dative of the thing for, on account of, which, 1 Corinthians 1:4; ὑπέρ τίνος, the genitive of person, Ephesians 1:16; ὑπέρ with the genitive of the thing, for, on account of, 1 Corinthians 10:30; Ephesians 5:20; the matter or ground of the thanksgiving is expressed by a following ὅτι: Luke 18:11; John 11:41; 1 Corinthians 1:14; 1 Thessalonians 2:13; Revelation 11:17; or is added asyndetically without ὅτι, 1 Corinthians 14:18 (λαλῶ L T Tr WH, for which R G λαλῶν, the participle declaring the cause which prompts to thanksgiving (Winers Grammar, 345f (324); Buttmann, 300 (258))). Once εὐχαριστεῖν τί, for a thing, in the passage 2 Corinthians 1:11 (cf. Buttmann, 148 (130); Winer's Grammar, 222 (209)); in the Fathers εὐχαριστεῖν τί is "to consecrate a thing by giving thanks, to 'bless'": ὁ ἐυχαριστηθεις ἄρτος καί οἶνος, Justin Martyr, Apology 1, 65 at the end; ἐυχαριστηθεισα τροφή, ibid.

c. 66; εἰσιν οἱ ἐυχαριστουσι ψιλον ὕδωρ, Clement of Alexandria, strom. i., p. 317, Sylb. edition; (cf. Suicer, Thesaurus i., 1269. "The words εὐχάριστος, εὐχαριστεῖν, εὐχαριστία, occur in St. Paul's writings alone of the apostolic Epistles" (Lightfoot; cf. Ellicott on Colossians 1:12)).