Lexical Definition

‎καθεύδω‎ katheúdō (kath-yoo'-do) to sleep ^G:V
from ‎κατά‎ and (to sleep)

(be a-)sleep.

• to lie down to rest, i.e. (by implication) to fall asleep (literally or figuratively)

Abbott-Smith

καθεύδω, [in LXX chiefly for שׁכב, Ge 28:13, Ps 87 (88):5, al.; also for יָשֵׁן, Ca 5:2, Da LXX TH 12:2, al.; for ישׁב, I Ki 19:9;]
to sleep: Mt 8:24 9:24 13:25 25:5 26:40, 43, 45, Mk 4:27, 38 5:39 14:37, 40, 41, Lk 8:52 22:46, I Th 5:7. Metaph.,
(a) of death (as Ps 87 (88):5, Da LXX TH 12:2): I Th 5:10 (cf. Mt 9:24, Mk 5:39, Lk 8:52, and v. Swete, Mk 5:39);
(b) of moral and spiritual insensibility: Mk 13:36, Eph 5:14, I Th 5:6.†
SYN.: κοιμάω.

Abbott-Smith References

Liddell-Scott-Jones

καθεύδω,

so also in Ionic dialect, [Refs 5th c.BC+]imperfect καθεῦδον [Refs 8th c.BC+]; ἐκάθευδον [Refs 5th c.BC+]: future καθευδήσω [Refs 5th c.BC+]aorist ἐκαθεύδησα (not in Attic dialect), [Refs 2nd c.AD+]; infinitive καθευδῆσαι [Refs]:— lie down to sleep, sleep, [Refs 8th c.BC+]; opposed to ἀγρυπνέω, ἐγρήγορα, [καθεύδων 2nd c.BC: Bion Bucolicus 1.71; κ. μάτην 4th-5th c.BC: Aeschylus Tragicus “Choephori” 881 ">Refs 6th c.BC+]; νυκτὸς κ. to sleep by night, [Refs 5th c.BC+]; κ. τὰς νύκτας to sleep all one's nights, [Refs 3rd c.BC+]; μαλακῶς, σκληρῶς κ., [Refs 4th c.BC+]; of male and female, ἵνα τώ γε καθεύδετον ἐν φιλότητι [Refs 8th c.BC+]: generally, pass the night, τὴν βουλὴν εἰς ἀκρόπολιν ἰέναι κἀκεῖ κ. [Refs 5th c.BC+]; κ. ἐπὶ ξύλου roost, of a fowl, [Refs 5th c.BC+]; ἐκ τοῦ καθεύδοντος from a sleeping state, [Refs 5th c.BC+]

__II metaphorically, lie asleep, lie idle, Χερί [Refs 5th c.BC+]; κ. τὸν βίον to be asleep all one's life, sleep away one's life, [Refs 5th c.BC+]; opposed to ἐνεργεῖν, [Refs 4th c.BC+]; opposed to προσέχειν τοῖς πράγμασι, [Refs 1st c.AD+]
__II.2 of things, lie still, be at rest, ἐλπίδες οὔπω κ. [Refs 5th c.BC+]
__II.3 of the sleep of death, καθεύδοντες ἐν τάφῳ [LXX+NT]

_{LSJ Scripture Refs: LXX.Ps.87.6* ☩ LXX.Dan.12.2 ☩ 1Thess.5.10}