press stud vs fixing

press stud and fixing both are nouns.

Word	Noun	Adjective	Verb	Adverb
press stud	Yes	No	No	No
fixing	Yes	No	No	No

As nouns, fixing is a hypernym of press stud; that is, fixing is a word with a broader meaning than press stud:

Other hypernyms of press stud include fastener, fastening, holdfast.

press stud (noun)	fixing (noun)
a fastener used on clothing; fastens with a snapping sound	the act of putting something in working order again
	the sterilization of an animal
	(histology) the preservation and hardening of a tissue sample to retain as nearly as possible the same relations they had in the living body
	restraint that attaches to something or holds something in place