G2121
εὔκαιρος
opportune
εὔ-καιρος, -ον [in LXX: Psa.104:27 (עֵת), 2Ma.14:29 2Mac 15:20-21, 3Ma.4:11 3Mac 5:44 * ;] timely, seasonable, suitable (Cremer, 740): ἡμέρα, Mrk.6:21 (or empty, as in Byz. and MGr.; see MM, Exp., xiv); βοήθεια, Heb.4:16.† (AS)
The KJV translates G2121 in the following manner:
convenient (2x), need (2x)
Full Thayer's lexicon entry
εὔκαιρος — eúkairos
εὔκαιρος, εὔκαιρον (εὖ and καιρός), seasonable, timely, opportune: βοήθεια, Heb 4:16; ἡμέρας εὐκαίρου, a convenient day, Mar 6:21. (2Ma 14:29; (Psalm 103:27; Sophocles O. C. 32); Theophrastus, Polybius, others.)
2 occurrences
Mark (1), Hebrews (1)