What does dictionary mean?
The definition of dictionary
Dic”tion*a*ry, n.; pl. Dictionaries.
Etym: [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.