The Collaborative International Dictionary of English v.0.48:

Exanthem \Ex*an"them\, n.
   Same as Exanthema.
   [1913 Webster]

WordNet (r) 3.0 (2006):

exanthem
    n 1: eruption on the skin occurring as a symptom of a disease
         [syn: exanthem, exanthema, skin eruption]