abscess (n.) Look up abscess at Dictionary.com
1610s, from Latin abscessus "an abscess" (Celsus), literally "a going away," from stem of abscedere "withdraw, depart, retire," from ab- "away" (see ab-) + cedere "to go" (see cede). The notion is that humors "go from" the body through the pus in the swelling.