The Collaborative International Dictionary of English v.0.48:

Ecthyma \Ec*thy"ma\, n.; pl. Ecthymata. [NL., fr. Gr. ?
   pimple, fr. ? to break out.] (Med.)
   A cutaneous eruption, consisting of large, round pustules,
   upon an indurated and inflamed base. --Dunglison.
   [1913 Webster]