The Collaborative International Dictionary of English v.0.48:

Sleeping \Sleep"ing\,
   a. & n. from Sleep.
   [1913 Webster]

   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.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

            Watching at the head of these that sleep. --Milton.
      [1913 Webster]

   2. Figuratively:
      (a) To be careless, inattentive, or uncouncerned; not to
          be vigilant; to live thoughtlessly.
          [1913 Webster]

                We sleep over our happiness.      --Atterbury.
          [1913 Webster]
      (b) To be dead; to lie in the grave.
          [1913 Webster]

                Them also which sleep in Jesus will God bring
                with him.                         --1 Thess. iv.
                                                  14.
          [1913 Webster]
      (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.
          [1913 Webster]

                How sweet the moonlight sleep upon this bank!
                                                  --Shak.
          [1913 Webster]

WordNet (r) 3.0 (2006):

sleeping
    adj 1: lying with head on paws as if sleeping [syn:
           dormant(ip), sleeping]
    n 1: the state of being asleep [ant: waking]
    2: quiet and inactive restfulness [syn: quiescence,
       quiescency, dormancy, sleeping]
    3: the suspension of consciousness and decrease in metabolic
       rate