Lexical Definition

‎ἀγρυπνέω‎ agrypnéō (ag-roop-neh'-o) be watchful G:V
ultimately from ‎Α‎ (as negative particle) and ‎ὕπνος‎

watch.

Usage: 9 forms in 11 verses
Form Translated As     In Verse(s)
ἀγρυπνοῦσιν watch Heb.13.17
ἀγρυπνοῦντεσ watching Eph.6.18
ἀγρυπνεῖτε do watch Mark.13.33Luke.21.36
ηγρύπνησεν stayed awake LXX.Job.21.32LXX.Ps.127.1
ηγρύπνησα I was sleepless LXX.Ps.102.7
ηγρύπνεισ sleepless LXX.2Sam.12.21
αγρυπνών being awake LXX.Prov.8.34
αγρυπνείτε Be awake LXX.Ezra.8.29
αγρυπνεί is sleepless LXX.Song.5.2

Abbott-Smith

ἀγρυπνέω, -ῶ (< ἄγρυπνος, seeking sleep ; < ἀγρεύω, ὕπνος), [in LXX chiefly for שׁקד;]

to be sleepless, wakeful (Theogn., Xen., al.); metaph. (LXX) = cl. ἐγρήγορα, to be watchful, vigilant: Mk 13:33, Lk 21:36, Eph 6:18, He 13:17.†
SYN.: γρηγορέω, q.v.; νήφω, associated with γ. in I Pe 5:8, expressing a wariness which results from self-control, a condition of moral, not merely mental alertness (v. M, Th., I, 5:6).

Abbott-Smith References

Book Refs
Mark 13:33
Luke 21:36
Ephesians 6:18
Hebrews 13:17
1 Peter 5:8

Liddell-Scott-Jones

ἀγρυπνέω-έω,

perfect ἠγρύπνηκα[Refs 5th c.BC+]:—lie awake, pass sleepless nights, [Refs 6th c.BC+]; opposed to καθεύδω, [Refs 5th c.BC+]; ἀγρυπνέωεῖν τὴν νύκτα to pass a sleepless night, [Refs 4th c.BC+]; οἱ -οῦντες sufferers from insomnia, [Refs 1st c.AD+]

__2 metaphorically, to be watchful, [LXX+NT]: with infinitive, μηθέν σε ἐνοχλήσειν[Refs]
__3 with accusative, lie awake and think of, τινά[Refs]

LSJ Scripture Refs: Mark.13.33Eph.6.18Heb.13.17LXX.Dan.9.14