can opener vs opener

can opener and opener both are nouns.

Word	Noun	Adjective	Verb	Adverb
can opener	Yes	No	No	No
opener	Yes	No	No	No

As nouns, opener is a hypernym of can opener; that is, opener is a word with a broader meaning than can opener:

can opener (noun)	opener (noun)
a device for cutting cans open	a hand tool used for opening sealed containers (bottles or cans)
	the first event in a series
	a person who unfastens or unwraps or opens