Emily Dickinson Lexicon

IM-POS'THUME, n. [impos'tume; This word is a corruption of apostem, L. apostema, Gr. αποστημα, from αφιστημι to separate, to withdraw, or to stand off; απο and ἱστημι, to stand.]

An abscess; a collection of pus or purulent matter in any part of an animal body. Encyc. [This word and its derivatives, being mere corruptions, might well be suffered to pass into oblivion.]