sleep (v.)

Old English slæpan "to be or fall asleep; be dormant or inactive" (class VII strong verb; past tense slep, past participle slæpen), from Proto-Germanic *slēpanan (source also of Old Saxon slapan, Old Frisian slepa, Middle Dutch slapen, Dutch slapen, Old High German slafen, German schlafen, Gothic slepan "to sleep"), from PIE *sleb- "to be weak, sleep," which perhaps is connected to PIE root *sleg- "be slack, be languid," the source of slack (adj.). Sleep with "do the sex act with" is in Old English:

Gif hwa fæmnan beswice unbeweddode, and hire mid slæpe ... [Laws of King Alfred, c. 900]

Related: Slept; sleeping. Sleep around is attested by 1928.

sleep (n.)

Old English slæp "sleep, sleepiness, inactivity," from Proto-Germanic *slepaz, from the root of sleep (v.); compare cognate Old Saxon slap, Old Frisian slep, Middle Dutch slæp, Dutch slaap, Old High German slaf, German Schlaf, Gothic sleps.

Personified in English from late 14c., on model of Latin Somnus, Greek Hypnos. Figurative use for "repose of death" was in Old English; to put (an animal) to sleep "kill painlessly" is recorded from 1923 (a similar imagery is in cemetery). Sleep deprivation attested from 1906. Sleep-walker "somnambulist" is attested from 1747; sleep-walking is from 1840. To be able to do something in (one's) sleep "easily" is recorded from 1953. Sleep apnea is by 1916.

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Definitions of sleep from WordNet
sleep (n.)
a natural and periodic state of rest during which consciousness of the world is suspended;
he didn't get enough sleep last night
Synonyms: slumber
sleep (n.)
a torpid state resembling deep sleep;
Synonyms: sopor
sleep (n.)
a period of time spent sleeping;
he felt better after a little sleep
Synonyms: nap
sleep (n.)
euphemisms for death (based on an analogy between lying in a bed and in a tomb);
they had to put their family pet to sleep
Synonyms: rest / eternal rest / eternal sleep / quietus
sleep (v.)
be asleep;
Synonyms: kip / slumber / log Z's / catch some Z's
sleep (v.)
be able to accommodate for sleeping;
This tent sleeps six people