sit vs sitter

sit is not a noun while sitter is a noun.

Word	Noun	Adjective	Verb	Adverb
sit	No	No	Yes	No
sitter	Yes	No	No	No

sit (noun)	sitter (noun)
	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

sit (verb)	sitter (verb)
serve in a specific professional capacity
be in a position in which one's upper body is largely upright and supported by one's backside
show to a seat; assign a seat for
take a seat
be in session
sit and travel on the back of animal, usually while controlling its motions
assume a posture as for artistic purposes
work or act as a baby-sitter
be around, often idly or without specific purpose
be located or situated somewhere