Source : Webster's Revised Unabridged Dictionary (1913)

Rationalist \Ra"tion*al*ist\, n. [Cf. F. rationaliste.]
   One who accepts rationalism as a theory or system; also,
   disparagingly, a false reasoner. See Citation under
   {Reasonist}.

Source : WordNet®

rationalist
     adj : of or relating to or characteristic of rationalism;
           "rationalist philosophy"

rationalist
     n : someone who emphasizes observable facts and excludes
         metaphysical speculation about origins or ultimate causes
         [syn: {positivist}]