This article is from the the official alt.spleen FAQ, by Andrew Stellman with numerous contributions by others.
Andrew says: NOTE: PLEASE DO NOT SEND ANY MAIL TO ME REQUESTING MEDICAL ADVICE! I AM NOT A DOCTOR, AND WILL NOT GIVE YOU ANY USEFUL INFORMATION.
The easiest way to answer that question is to consult the dictionary:
Word SPLEEN (SPLEEN) n. Definition --n. 1. a. One of the largest lymphoid structures in human beings, a visceral organ composed of a white pulp of lymphatic nodules and tissue and a red pulp of venous sinusoids in a framework of fibrous partitions lying on the left side below the diaphragm, functioning as a blood filter and to store blood. b. A homologous organ or tissue in other vertebrates. 2. Obs. a. The seat of emotions or passions. b. A whim; caprice. 3. Archaic. Melancholy. 4. Ill temper. spleeny --adj. Etymology ME splene < OFr. esplen < Lat. splen < Gk splen. Domain Everyday conversation
As everyone knows, the spleen is more than just a part of your lymphatic system. When properly cared for and coddled, a spleen can lead to a more fulfilling, and often more interesting life.
And, according to linguist Matthew Messner (email@example.com):
Word SPLENDID (SPLEHN'-did) Definition --adj. of, or pertaining to, the spleen.