mamma's boy vs mama's boy

mamma's boy and mama's boy both are nouns.

Word	Noun	Adjective	Verb	Adverb
mamma's boy	Yes	No	No	No
mama's boy	Yes	No	No	No

As nouns, mamma's boy and mama's boy are synonyms defined as:

mamma's boy and mama's boy: a boy excessively attached to his mother; lacking normal masculine interests

Other synonyms of mamma's boy include mother's boy.

mamma's boy (noun)	mama's boy (noun)
a boy excessively attached to his mother; lacking normal masculine interests	a boy excessively attached to his mother; lacking normal masculine interests