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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.