Extended Strong's Greek Lexicon (Abbott-Smith based)
to lose heart
Usage: ἐκκακέω, -ῶ, see: ἐνκακέω. ἐν-κακέω, -ῶ (LTr., ἐγκ-; Rec. ἐκκ-; cf. WH, Notes, 157 f.; κακός, cowardly), [in Sm.: Gen.27:46, Num.21:5, Pro.3:11, Isa.7:16 *;] to lose heart : Luk.18:1, 2Co.4:1,16, Gal.6:9, Eph.3:13, 2Th.3:13 (Cremer, 330).† (AS)