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[Greek splēno-, from splēn, spleen.]
1. a highly vascular, glandular, ductless organ, situated in humans at the cardiac end of the stomach, serving chiefly in the formation of mature lymphocytes, in the destruction of worn-out red blood cells, and as a reservoir for blood.
2. (formerly) this organ conceived of as the seat of spirit and courage or of such emotions as mirth, ill humor, melancholy, etc.
3. ill humor, peevish temper, or spite.
4. Archaic. melancholy.
5. Obs. caprice.
[1250–1300; Middle English (< Old French esplen) < Latin splēn < Greek splḗn; akin to Latin liēn spleen]