Lexical Definition

‎αἰφνίδιος‎ aiphnídios (aheef-nid'-ee-os) sudden G:A
from a compound of ‎Α‎ (as a negative particle) and ‎φαίνω‎ (compare ‎ἐξαίφνης‎) (meaning non-apparent)

sudden, unawares.

Usage: 1 form in 2 verses
Form Translated As     In Verse(s)
αἰφνίδιοσ suddenly Luke.21.341Thess.5.3

Abbott-Smith

** αἰφνίδιος (in Lk 21:34, ἐφν- WH; v. M, Pr., 35), -ον (< αἴφνης = ἄφνως, suddenly), [in LXX: Wi 17:15, II Mac 14:17, III Mac 3:24*;]
sudden, unexpected: Lk 21:34, I Th 5:3.†

Abbott-Smith References

Book Refs
Luke 21:34
1 Thessalonians 5:3

Liddell-Scott-Jones

αἰφνίδιος, ον,

unforeseen, sudden, [Refs 5th c.BC+]. adverb -ίως[Refs] also -ιον [Refs 1st c.AD+]. αἰφνιδιοτυχής, ές, profiting by strokes of good fortune, [Refs]