short temper vs spleen

short temper and spleen both are nouns.

Word	Noun	Adjective	Verb	Adverb
short temper	Yes	No	No	No
spleen	Yes	No	No	No

As nouns, short temper and spleen are synonyms defined as:

Other synonyms of short temper include irascibility, quick temper.

short temper (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