Abbott-Smith Manual Greek Lexicon
ἔννυχος (G1773)
1 (KJV) ἔννυχος , -ον ( νύξ ), [in LXX: III Mac 5:5 * ;] (in cl. poët.; prose in late Gk. only) nightly . Neut., adverbially, ἔννυχα (Rec. -χον ), by night : Mk 1:35 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain