inion vs craniometric point

inion and craniometric point both are nouns.

Word	Noun	Adjective	Verb	Adverb
inion	Yes	No	No	No
craniometric point	Yes	No	No	No

As nouns, craniometric point is a hypernym of inion; that is, craniometric point is a word with a broader meaning than inion:

inion: the craniometric point that is the most prominent point at the back of the head (at the occipital protuberance)
craniometric point: a landmark on the skull from which craniometric measurements can be taken

inion (noun)	craniometric point (noun)
the craniometric point that is the most prominent point at the back of the head (at the occipital protuberance)	a landmark on the skull from which craniometric measurements can be taken