tummy vs tum

tummy and tum both are nouns.

Word	Noun	Adjective	Verb	Adverb
tummy	Yes	No	No	No
tum	Yes	No	No	No

As nouns, tummy and tum are synonyms defined as:

tummy and tum: an enlarged and muscular saclike organ of the alimentary canal; the principal organ of digestion

Other synonyms of tummy include breadbasket, stomach.

tummy (noun)	tum (noun)
an enlarged and muscular saclike organ of the alimentary canal; the principal organ of digestion	an enlarged and muscular saclike organ of the alimentary canal; the principal organ of digestion
slang for a paunch