- spleen (n.)
- c.1300, from Old French esplen, from Latin splen, from Greek splen, from PIE *splegh- (cf. Sanskrit plihan-, Avestan sperezan, Armenian p'aicaln, Latin lien, Old Church Slavonic slezena, Lithuanian bluznis, Old Prussian blusne, Old Irish selg "spleen"). Regarded in medieval physiology as the seat of morose feelings and bad temper. Hence figurative sense of "violent ill-temper" (1590s).