os scaphoideum vs scaphoid bone

os scaphoideum and scaphoid bone both are nouns.

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

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

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

Other synonyms of os scaphoideum include navicular.

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