mildness vs mild

mildness is a noun but mild is not a noun.

Word	Noun	Adjective	Verb	Adverb
mildness	Yes	No	No	No
mild	No	Yes	No	No

mildness (noun)	mild (noun)
mercifulness as a consequence of being lenient or tolerant
acting in a manner that is gentle and mild and even-tempered
good weather with comfortable temperatures

mildness (adjective)	mild (adjective)
	moderate in type or degree or effect or force; far from extreme
	mild and pleasant
	humble in spirit or manner; suggesting retiring mildness or even cowed submissiveness