a. A large, highly vascular lymphoid organ, located in the human body to the left of the stomach below the diaphragm, that serves as a reservoir for blood, destroys old red blood cells, and contains lymphocytes that combat blood-borne antigens.
b. A homologous organ or tissue in other vertebrates.
2. Obsolete This organ conceived as the seat of emotions or passions.
3. Ill temper: vent one's spleen.
4. Archaic Melancholy.
5. Obsolete A whim; a caprice.
[Middle English splen, from Old French esplen, from Latin splēn, from Greek.]
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