Source : Webster's Revised Unabridged Dictionary (1913)

Hypertrophy \Hy*per"tro*phy\, n. [Gr. "ype`r over, beyond + ?
   nourishment, fr. ? to nourish: cf. F. hypertrophie.] (Med. &
   Biol.)
   A condition of overgrowth or excessive development of an
   organ or part; -- the opposite of {atrophy}.

Source : WordNet®

hypertrophy
     n : abnormal enlargement of a body part or organ
     v : undergo hypertrophy; "muscles can hypertrophy when people
         take steroids"
     [also: {hypertrophied}]