acetabular vs acetabulum

acetabular is not a noun while acetabulum is a noun.

Word	Noun	Adjective	Verb	Adverb
acetabular	No	Yes	No	No
acetabulum	Yes	No	No	No

acetabular (noun)	acetabulum (noun)
	the cup-shaped hollow in the hipbone into which the head of the femur fits to form a ball-and-socket joint

acetabular (adjective)	acetabulum (adjective)
of the cup-shaped socket that receives the head of the thigh bone