Source : Webster's Revised Unabridged Dictionary (1913)

Caveat \Ca"ve*at\, n. [L. caved let him beware, pres. subj. of
   cavere to be on one's guard to, beware.]
   1. (Law) A notice given by an interested party to some
      officer not to do a certain act until the party is heard
      in opposition; as, a caveat entered in a probate court to
      stop the proving of a will or the taking out of letters of
      administration, etc. --Bouvier.

   2. (U. S. Patent Laws) A description of some invention,
      designed to be patented, lodged in the patent office
      before the patent right is applied for, and operating as a
      bar to the issue of letters patent to any other person,
      respecting the same invention.

   Note: A caveat is operative for one year only, but may be
         renewed.

   3. Intimation of caution; warning; protest.

            We think it right to enter our caveat against a
            conclusion.                           --Jeffrey.

   {Caveat emptor} [L.] (Law), let the purchaser beware, i. e.,
      let him examine the article he is buying, and act on his
      own judgment.

Source : WordNet®

caveat emptor
     n : a commercial principle that without a warranty the buyer
         takes upon himself the risk of quality