ethmoidal sinus vs ethmoid sinus

ethmoidal sinus and ethmoid sinus both are nouns.

Word	Noun	Adjective	Verb	Adverb
ethmoidal sinus	Yes	No	No	No
ethmoid sinus	Yes	No	No	No

As nouns, ethmoidal sinus and ethmoid sinus are synonyms defined as:

ethmoidal sinus and ethmoid sinus: a sinus of the meatuses of the nasal cavity (behind the bridge of the nose)

Other synonyms of ethmoidal sinus include sinus ethmoidales.

ethmoidal sinus (noun)	ethmoid sinus (noun)
a sinus of the meatuses of the nasal cavity (behind the bridge of the nose)	a sinus of the meatuses of the nasal cavity (behind the bridge of the nose)