hyoid bone vs os hyoideum

hyoid bone and os hyoideum both are nouns.

Word	Noun	Adjective	Verb	Adverb
hyoid bone	Yes	No	No	No
os hyoideum	Yes	No	No	No

As nouns, hyoid bone and os hyoideum are synonyms defined as:

hyoid bone and os hyoideum: a U-shaped bone at the base of the tongue that supports the tongue muscles

Other synonyms of hyoid bone include hyoid.

hyoid bone (noun)	os hyoideum (noun)
a U-shaped bone at the base of the tongue that supports the tongue muscles	a U-shaped bone at the base of the tongue that supports the tongue muscles