Source : Webster's Revised Unabridged Dictionary (1913)

Sleep \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.

Sleeping \Sleep"ing\,
   a. & n. from {Sleep}.

   {Sleeping car}, a railway car or carrriage, arranged with
      apartments and berths for sleeping.

   {Sleeping partner} (Com.), a dormant partner. See under
      {Dormant}.

   {Sleeping table} (Mining), a stationary inclined platform on
      which pulverized ore is washed; a kind of buddle.

Source : WordNet®

sleeping
     n 1: the state of being asleep [ant: {waking}]
     2: quiet and inactive restfulness [syn: {quiescence}, {quiescency},
         {dormancy}]
     3: the suspension of consciousness and decrease in metabolic
        rate

sleeping
     adj : lying with head on paws as if sleeping [syn: {dormant(ip)}]