sesamoid vs os sesamoideum

sesamoid and os sesamoideum both are nouns.

Word	Noun	Adjective	Verb	Adverb
sesamoid	Yes	No	No	No
os sesamoideum	Yes	No	No	No

As nouns, sesamoid and os sesamoideum are synonyms defined as:

sesamoid and os sesamoideum: any of several small round bones formed in a tendon where it passes over a joint

Other synonyms of sesamoid include sesamoid bone.

sesamoid (noun)	os sesamoideum (noun)
any of several small round bones formed in a tendon where it passes over a joint	any of several small round bones formed in a tendon where it passes over a joint