sinciput vs os

sinciput and os both are nouns.

Word	Noun	Adjective	Verb	Adverb
sinciput	Yes	No	No	No
os	Yes	No	No	No

As nouns, os is a hypernym of sinciput; that is, os is a word with a broader meaning than sinciput:

Other hypernyms of sinciput include bone.

sinciput (noun)	os (noun)
the front part of the head or skull (including the forehead)	rigid connective tissue that makes up the skeleton of vertebrates
	a mouth or mouthlike opening