The Collaborative International Dictionary of English v.0.48:

Eczema \Ec"ze*ma\, n. [NL., fr. Gr. 'e`kzema; "ek out + zei^n to
   boil.] (Med.)
   An inflammatory disease of the skin, characterized by the
   presence of redness and itching, an eruption of small
   vesicles, and the discharge of a watery exudation, which
   often dries up, leaving the skin covered with crusts; --
   called also tetter, milk crust, and salt rheum.
   [1913 Webster]

WordNet (r) 3.0 (2006):

eczema
    n 1: generic term for inflammatory conditions of the skin;
         particularly with vesiculation in the acute stages