Source : Webster's Revised Unabridged Dictionary (1913)

Dictionary \Dic"tion*a*ry\, n.; pl. {Dictionaries}. [Cf. F.
   dictionnaire. See {Diction}.]
   1. A book containing the words of a language, arranged
      alphabetically, with explanations of their meanings; a
      lexicon; a vocabulary; a wordbook.

            I applied myself to the perusal of our writers; and
            noting whatever might be of use to ascertain or
            illustrate any word or phrase, accumulated in time
            the materials of a dictionary.        --Johnson.

   2. Hence, a book containing the words belonging to any system
      or province of knowledge, arranged alphabetically; as, a
      dictionary of medicine or of botany; a biographical
      dictionary.

Source : WordNet®

dictionary
     n : a reference book containing an alphabetical list of words
         with information about them [syn: {lexicon}]