Abbott-Smith Manual Greek Lexicon
ἀσφαλής (G804)
5 ἀσφαλής , -ές ( ἀ- neg., σφάλλω , to trip up ), [in LXX for אשׁר pu., etc.;] certain , secure , safe : Ac 21:34 22:30 25:26 , Phl 3:1 , He 6:19 (MM, s.v.).†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain