irascibility vs spleen

irascibility and spleen both are nouns.

Word	Noun	Adjective	Verb	Adverb
irascibility	Yes	No	No	No
spleen	Yes	No	No	No

As nouns, irascibility and spleen are synonyms defined as:

Other synonyms of irascibility include quick temper, short temper.

irascibility (noun)	spleen (noun)
a feeling of resentful anger	a large dark-red oval organ on the left side of the body between the stomach and the diaphragm; produces cells involved in immune responses
	a feeling of resentful anger