mastoid vs mastoid bone

mastoid and mastoid bone both are nouns.

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

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

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

Other synonyms of mastoid include mastoid process, mastoidal.

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