fervor vs fervidness

fervor and fervidness both are nouns.

Word	Noun	Adjective	Verb	Adverb
fervor	Yes	No	No	No
fervidness	Yes	No	No	No

As nouns, fervor and fervidness are synonyms defined as:

Other synonyms of fervor include ardor, ardour, fervency, fervour, fire.

fervor (noun)	fervidness (noun)
feelings of great warmth and intensity	feelings of great warmth and intensity
the state of being emotionally aroused and worked up