scaphoid bone vs os scaphoideum

scaphoid bone and os scaphoideum both are nouns.

Word	Noun	Adjective	Verb	Adverb
scaphoid bone	Yes	No	No	No
os scaphoideum	Yes	No	No	No

As nouns, scaphoid bone and os scaphoideum are synonyms defined as:

scaphoid bone and os scaphoideum: the largest wrist bone on the thumb side

Other synonyms of scaphoid bone include navicular.

scaphoid bone (noun)	os scaphoideum (noun)
the largest wrist bone on the thumb side	the largest wrist bone on the thumb side