spleen vs irascibility

spleen and irascibility both are nouns.

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

As nouns, spleen and irascibility are synonyms defined as:

Other synonyms of spleen include quick temper, short temper.

spleen (noun)	irascibility (noun)
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
a feeling of resentful anger