The Collaborative International Dictionary of English v.0.48:

Mania \Ma"ni*a\, n. [L. mania, Gr. ?, fr. ? to rage; cf. OE.
   manie, F. manie. Cf. Mind, n., Necromancy.]
   1. Violent derangement of mind; madness; insanity. Cf.
      Delirium.
      [1913 Webster]

   2. Excessive or unreasonable desire; insane passion affecting
      one or many people; as, the tulip mania.
      [1913 Webster]

   Mania a potu [L.], madness from drinking; delirium tremens.
      [1913 Webster]

   Syn: Insanity; derangement; madness; lunacy; alienation;
        aberration; delirium; frenzy. See Insanity.
        [1913 Webster]

WordNet (r) 3.0 (2006):

mania
    n 1: an irrational but irresistible motive for a belief or
         action [syn: mania, passion, cacoethes]
    2: a mood disorder; an affective disorder in which the victim
       tends to respond excessively and sometimes violently [syn:
       mania, manic disorder]