1753, from Greek ekzema, literally "something thrown out by heat," from ekzein "to boil over, break out," from ek "out" (see ex-) + zein "to boil," from PIE root *yes- "to boil, foam, bubble" (see yeast). Said to have been the name given by ancient physicians to "any fiery pustule on the skin" [Chambers' "Cyclopaedia"].