Source : Webster's Revised Unabridged Dictionary (1913)

Definition \Def`i*ni"tion\, n. [L. definitio: cf. F.
   d['e]finition.]
   1. The act of defining; determination of the limits; as, a
      telescope accurate in definition.

   2. Act of ascertaining and explaining the signification; a
      description of a thing by its properties; an explanation
      of the meaning of a word or term; as, the definition of
      ``circle;'' the definition of ``wit;'' an exact
      definition; a loose definition.

            Definition being nothing but making another
            understand by words what the term defined stands
            for.                                  --Locke.

   3. Description; sort. [R.] ``A new creature of another
      definition.'' --Jer. Taylor.

   4. (Logic) An exact enunciation of the constituents which
      make up the logical essence.

   5. (Opt.) Distinctness or clearness, as of an image formed by
      an optical instrument; precision in detail.

   Syn: {Definition}, {Explanation}, {Description}.

   Usage: A definition is designed to settle a thing in its
          compass and extent; an explanation is intended to
          remove some obscurity or misunderstanding, and is
          therefore more extended and minute; a description
          enters into striking particulars with a view to
          interest or impress by graphic effect. It is not
          therefore true, though often said, that description is
          only an extended definition. ``Logicians distinguish
          definitions into essential and accidental. An
          essential definition states what are regarded as the
          constituent parts of the essence of that which is to
          be defined; and an accidental definition lays down
          what are regarded as circumstances belonging to it,
          viz., properties or accidents, such as causes,
          effects, etc.'' --Whately.

Source : WordNet®

definition
     n 1: a concise explanation of the meaning of a word or phrase or
          symbol
     2: clarity of outline; "exercise had give his muscles superior
        definition"