foramen magnum vs foramen

foramen magnum and foramen both are nouns.

Word	Noun	Adjective	Verb	Adverb
foramen magnum	Yes	No	No	No
foramen	Yes	No	No	No

As nouns, foramen is a hypernym of foramen magnum; that is, foramen is a word with a broader meaning than foramen magnum:

foramen magnum: the large opening at the base of the cranium through which the spinal cord passes
foramen: a natural opening or perforation through a bone or a membranous structure

Other hypernyms of foramen magnum include hiatus.

foramen magnum (noun)	foramen (noun)
the large opening at the base of the cranium through which the spinal cord passes	a natural opening or perforation through a bone or a membranous structure