Quick Definition
I fall asleep
Strong's Definition
properly, to become awake, i.e. (by implication) to drop (off) in slumber
Derivation: from a compound of G575 (ἀπό) and G5258 (ὕπνος);
KJV Usage: fall asleep
Thayer's Greek Lexicon
ἀφυπνόω, ἀφύπνω: 1 aorist ἀφυπνωσα; (ὑπνόω to put to sleep, to sleep);
a. to awaken from sleep (Anthol. Pal. 9, 517, 5 ).
b. to fall asleep, to fall off to sleep: Luk_8:23; for this the ancient Greeks used καθυπνόω; see Lobeck ad Phryn., p. 224. (Hermas, vis. 1, 1 [ET].)
Mounce Concise Greek Dictionary
ἀφυπνόω aphypnoō 1x
to awake from sleep; in NT to go off into sleep, fall asleep, Luk_8:23
Abbott-Smith Greek Lexicon
**† ἀφ -υπιόω , -ῶ
( < ὑπνόω , to put to sleep ),
[in Al. : Gen_28:11 * ;]
1. to awake from sleep ( Anth .).
2. = cl . καθυπνόω ( MM , s.v. ), to fall asleep: Luk_8:23 .†
Moulton & Milligan — Vocabulary of the Greek NT
ἀφυπνόω [page 99]
Plummer on Luk_8:23 says the use = fall asleep is medical and late : unfortunately he gives no evidence of the former (nor does Hobart mention it), but the citation from Heliodorus is to be noted. Lobeck Phryn. p. 224 gives others. The transference of an ἀπό compound from the end of an action to the beginning of it is seen also in ἄφιξις ( q. v. ) : in neither case is Luke likely to have started the change of meaning, but our evidence is still scantier here than there.
Liddell-Scott — Intermediate Greek Lexicon
ἀφυπνόω "to wake from sleep", Anth. "to fall asleep", NTest.
STEPBible — Tyndale Abridged Greek Lexicon
ἀφ-υπιόω, -ῶ
(ὑπνόω, to put to sleep), [in Al.: Gen.28:11 * ;]
__1. to awake from sleep (Anth.).
__2. = cl. καθυπνόω (MM, see word), to fall asleep: Luk.8:23.†
(AS)