Source : Webster's Revised Unabridged Dictionary (1913)

Fad \Fad\, n. [Cf. {Faddle}.]
   A hobby; freak; whim. -- {Fad"dist}, n.

         It is your favorite fad to draw plans.   --G. Eliot.

Source : WordNet®

faddist
     n : a person who subscribes to a variety of fads