Mother Hubbard vs muumuu

Mother Hubbard and muumuu both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mother Hubbard	Yes	No	No	No
muumuu	Yes	No	No	No

As nouns, Mother Hubbard and muumuu are synonyms defined as:

Mother Hubbard (noun)	muumuu (noun)
a woman's loose unbelted dress	a woman's loose unbelted dress