broody hen vs sitter

broody hen and sitter both are nouns.

Word	Noun	Adjective	Verb	Adverb
broody hen	Yes	No	No	No
sitter	Yes	No	No	No

As nouns, broody hen and sitter are synonyms defined as:

Other synonyms of broody hen include brood hen, broody, setting hen.

broody hen (noun)	sitter (noun)
a domestic hen ready to brood	a domestic hen ready to brood
	a person engaged to care for children when the parents are not home
	an organism (person or animal) that sits
	a person who poses for a painter or sculptor