1. [n]  euphemisms for death (based on an analogy between lying in a bed and in a tomb); "she was laid to rest beside her husband"; "they had to put their family pet to sleep"
2. [n]  a natural and periodic state of rest during which consciousness of the world is suspended; "he didn't get enough sleep last night"; "calm as a child in dreamless slumber"
3. [n]  a torpid state resembling sleep
4. [n]  a period of time spent sleeping; "he felt better after a little sleep"; "a brief nap"
5. [v]  be asleep
6. [v]  be able to accommodate for sleeping; "This tent sleeps six people"

Sleep
Sleep

more details ...

1. \Sleep\, obs.
   imp. of Sleep. Slept. --Chaucer.
   

2. \Sleep\, v. i. [imp. & p. p. {Slept}; p. pr. & vb. n.
   {Sleeping}.] [OE. slepen, AS. sl?pan; akin to OFries. sl?pa,
   OS. sl[=a]pan, D. slapen, OHG. sl[=a]fan, G. schlafen, Goth.
   sl?pan, and G. schlaff slack, loose, and L. labi to glide,
   slide, labare to totter. Cf. {Lapse}.]
   1. To take rest by a suspension of the voluntary exercise of
      the powers of the body and mind, and an apathy of the
      organs of sense; to slumber. --Chaucer.
            Watching at the head of these that sleep. --Milton.
   2. Figuratively:
      (a) To be careless, inattentive, or uncouncerned; not to
          be vigilant; to live thoughtlessly.
                We sleep over our happiness.      --Atterbury.
      (b) To be dead; to lie in the grave.
                Them also which sleep in Jesus will God bring
                with him.                         --1 Thess. iv.
                                                  14.
      (c) To be, or appear to be, in repose; to be quiet; to be
          unemployed, unused, or unagitated; to rest; to lie
          dormant; as, a question sleeps for the present; the
          law sleeps.
                How sweet the moonlight sleep upon this bank!
                                                  --Shak.
   

3. \Sleep\, v. t.
   1. To be slumbering in; -- followed by a cognate object; as,
      to sleep a dreamless sleep. --Tennyson.
   2. To give sleep to; to furnish with accomodations for
      sleeping; to lodge. [R.] --Blackw. Mag.
   {To sleep away}, to spend in sleep; as, to sleep away
      precious time.
   {To sleep off}, to become free from by sleep; as, to sleep
      off drunkeness or fatigue.
   

4. \Sleep\, n. [AS. sl[=ae]p; akin to OFries. sl[=e]p, OS.
   sl[=a]p, D. slaap, OHG. sl[=a]f, G. schlaf, Goth. sl[=e]ps.
   See {Sleep}, v. i.]
   A natural and healthy, but temporary and periodical,
   suspension of the functions of the organs of sense, as well
   as of those of the voluntary and rational soul; that state of
   the animal in which there is a lessened acuteness of sensory
   perception, a confusion of ideas, and a loss of mental
   control, followed by a more or less unconscious state. ``A
   man that waketh of his sleep.'' --Chaucer.
         O sleep, thou ape of death.              --Shak.
   Note: Sleep is attended by a relaxation of the muscles, and
         the absence of voluntary activity for any rational
         objects or purpose. The pulse is slower, the
         respiratory movements fewer in number but more
         profound, and there is less blood in the cerebral
         vessels. It is susceptible of greater or less intensity
         or completeness in its control of the powers.
   {Sleep of plants} (Bot.), a state of plants, usually at
      night, when their leaflets approach each other, and the
      flowers close and droop, or are covered by the folded
      leaves.
   Syn: Slumber; repose; rest; nap; doze; drowse.
   

1. (Or "block") When a process on a multitasking system asks the scheduler to deactivate it until some given external event (e.g. an interrupt or a specified time delay) occurs.

The alternative is to poll or "busy wait" for the event but this uses processing power.

Also used in the phrase "sleep on" (or "block on") some external event, meaning to wait for it.

E.g. the Unix command of the same name which pauses the current process for a given number of seconds.

2. To go into partial deactivation to save power.

[Jargon File]