The Collaborative International Dictionary of English v.0.48:

nymphomania \nym`pho*ma"ni*a\ (n[i^]m`f[-o]*m[=a]"n[i^]*[.a]),
   n. [Gr. ny`mfh a bride + mani`a madness.] (Med.)
   An uncontrollable excessive sexual desire in women,
   constituting a true disease.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nymphomania
    n 1: abnormally intense sexual desire in women