A Spleen

1. (anatomy, immunology) In vertebrates, including humans, a ductless vascular gland, located in the left upper abdomen near the stomach, which destroys old red blood cells, removes debris from the bloodstream, acts as a reservoir of blood, and produces lymphocytes.
2. (archaic, except in the set phrase "to vent one's spleen") A bad mood; spitefulness.
3. (obsolete, rare) A sudden motion or action; a fit; a freak; a whim.
4. (obsolete) Melancholy; hypochondriacal affections.
5. A fit of immoderate laughter or merriment.

milt (now chiefly of animals); lien (uncommon)