Source : Webster's Revised Unabridged Dictionary (1913)

Thousand \Thou"sand\, n. [OE. [thorn]ousend, [thorn]usend, AS.
   [thorn][=u]send; akin to OS. th[=u]sundig, th[=u]sind,
   OFries. thusend, D. duizend, G. tausend, OHG. t[=u]sunt,
   d[=u]sunt, Icel. [thorn][=u]sund, [thorn][=u]shund, Sw.
   tusen, Dan. tusind, Goth. [thorn][=u]sundi, Lith. tukstantis,
   Russ. tuisiacha; of uncertain origin.]
   1. The number of ten hundred; a collection or sum consisting
      of ten times one hundred units or objects.

   2. Hence, indefinitely, a great number.

            A thousand shall fall at thy side, and ten thousand
            at thy right hand.                    --Ps. xci. 7.

   Note: The word thousand often takes a plural form. See the
         Note under {Hundred}.

   3. A symbol representing one thousand units; as, 1,000, M or
      CI[Crev].

Thousand \Thou"sand\, a.
   1. Consisting of ten hundred; being ten times one hundred.

   2. Hence, consisting of a great number indefinitely.
      ``Perplexed with a thousand cares.'' --Shak.

Source : WordNet®

thousand
     adj : denoting a quantity consisting of 1,000 items or units [syn:
            {a thousand}, {one thousand}, {1000}, {m}, {k}]

thousand
     n : the cardinal number that is the product of 10 and 100 [syn:
         {one thousand}, {1000}, {M}, {K}, {chiliad}, {G}, {grand},
          {thou}, {yard}]