mastoid bone vs mastoid

mastoid bone and mastoid both are nouns.

Word	Noun	Adjective	Verb	Adverb
mastoid bone	Yes	No	No	No
mastoid	Yes	Yes	No	No

As nouns, mastoid bone and mastoid are synonyms defined as:

mastoid bone and mastoid: process of the temporal bone behind the ear at the base of the skull

Other synonyms of mastoid bone include mastoid process, mastoidal.

mastoid bone (noun)	mastoid (noun)
process of the temporal bone behind the ear at the base of the skull	process of the temporal bone behind the ear at the base of the skull

mastoid bone (adjective)	mastoid (adjective)
	relating to or resembling a nipple
	of or relating to or in the region of the mastoid process