The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

            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.
      [1913 Webster]

   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.
      [1913 Webster]