- (anatomy, immunology) In vertebrates, including humans, a ductless vascular gland, located in the left upper abdomen near the stomach, which destroys old red blood cells, removes debris from the bloodstream, acts as a reservoir of blood, and produces lymphocytes.
- (archaic, except in the set phrase "to vent one's spleen") A bad mood; spitefulness.
- 1709, [Alexander Pope], An Essay on Criticism, London: Printed for W. Lewis […], published 1711, OCLC 15810849 ↗:
- In noble minds some dregs remain, / Not yet purged off, of spleen and sour disdain.
- (obsolete, rare) A sudden motion or action; a fit; a freak; a whim.
- 1593, [William Shakespeare], Venvs and Adonis, London: Imprinted by Richard Field, […], OCLC 837166078 ↗; Shakespeare’s Venvs & Adonis: […], 4th edition, London: J[oseph] M[alaby] Dent and Co. […], 1896, OCLC 19803734 ↗:
- A thousand spleens bear her a thousand ways.
- Brief as the lightning in the collied night; That, in a spleen, unfolds both heaven and Earth
- (obsolete) Melancholy; hypochondriacal affections.
- 1712 May, [Alexander Pope], “The Rape of the Locke. An Heroi-comical Poem.”, in Miscellaneous Poems and Translations. By Several Hands, London: Printed for Bernard Lintott […], OCLC 228744960 ↗:
- Bodies changed to various forms by spleen.
- There is a luxury in self-dispraise: / And inward self-disparagement affords / To meditative spleen a grateful feast.
- A fit of immoderate laughter or merriment.
- c. 1601–1602, William Shakespeare, “Twelfe Night, or VVhat You VVill”, in Mr. William Shakespeares Comedies, Histories, & Tragedies: Published According to the True Originall Copies (First Folio), London: Printed by Isaac Iaggard, and Ed[ward] Blount, published 1623, OCLC 606515358 ↗, [Act III, scene ii]:
- By virtue, thou enforcest laughter ; thy silly thought, my spleen
spleen (spleens, present participle spleening; past and past participle spleened)
- (obsolete, transitive) To dislike.