hay fever vs pollinosis

hay fever and pollinosis both are nouns.

Word	Noun	Adjective	Verb	Adverb
hay fever	Yes	No	No	No
pollinosis	Yes	No	No	No

As nouns, hay fever and pollinosis are synonyms defined as:

hay fever and pollinosis: a seasonal rhinitis resulting from an allergic reaction to pollen

hay fever (noun)	pollinosis (noun)
a seasonal rhinitis resulting from an allergic reaction to pollen	a seasonal rhinitis resulting from an allergic reaction to pollen