Oxford Advanced American Dictionary

Definition of sleep noun from the Oxford Advanced Learner's Dictionary

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sleep

noun
sleep pronunciation English sliːp sleep pronunciation American sliːp
 
1 [uncountable] the natural state of rest in which your eyes are closed, your body is not active, and your mind is not consciousI need to get some sleep.I didn't get much sleep last night.Can you give me something to help me get to sleep (= start sleeping)?Go to sleep—it's late.He cried out in his sleep.Anxiety can be caused by lack of sleep.His talk nearly sent me to sleep (= it was boring).Try to go back to sleep.2 [singular] a period of sleepDid you have a good sleep?Ros fell into a deep sleep.I'll feel better after a good night's sleep (= a night when I sleep well).3 [uncountable] (informal) the substance that sometimes forms in the corners of your eyes after you have been sleepingNed rubbed the sleep from his eyes.
Idioms

be able to do something in your sleep

(informal) to be able to do something very easily because you have done it many times beforeI haven't done many portraits, but I could paint landscapes in my sleep.
Idioms

go to sleep

(informal) if part of your body goes to sleep, you lose the sense of feeling in it, usually because it has been in the same position for too longMy foot's gone to sleep.

not lose sleep/lose no sleep over something

to not worry much about something
It's not worth losing sleep over.

put somebody to sleep

(informal) to make somebody unconscious before an operation by using drugs (called an anaesthetic)

put something to sleep

to kill a sick or injured animal by giving it drugs so that it dies without pain. People say put to sleep to avoid saying kill.
more at not get/have a wink of sleep at wink noun