spleen

UK: /ˈspliːn/ US: /splin/ ,(splēn)

WordReference Random House Learner's Dictionary of American English © 2025

spleen /splin/   n. 

1. Anatomy [countable] an organ in the body near the stomach and heart, that destroys worn-out red blood cells and is a reservoir for blood.
2. ill humor;
   angry, impatient temper;
   spite:
   [uncountable] to vent one's spleen by shouting at someone else.

WordReference Random House Unabridged Dictionary of American English © 2025

spleen  (splēn), n. 

1. Anatomy 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. [Obs.] 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.

• Greek splé̄n; akin to Sanskrit plīhan, Latin liēn spleen
• Latin splēn
• Middle English 1250–1300

spleen′ish, adj. 
Synonyms

• 3. petulance, rancor, acrimoniousness; wrath, ire, anger.

Collins Concise English Dictionary © HarperCollins Publishers::

spleen / spliːn/ noun

1. a spongy, highly vascular organ situated near the stomach in humans. It forms lymphocytes, produces antibodies, aids in destroying worn-out red blood cells, and filters bacteria and foreign particles from the blood
2. the corresponding organ in other animals
3. spitefulness or ill humour; peevishness: to vent one's spleen
4. the organ in the human body considered to be the seat of the emotions
5. 
   another word for melancholy

Etymology: 13th Century: from Old French esplen, from Latin splēn, from Greek; related to Latin lien spleen

ˈspleenish, ˈspleeny adjective