firmness vs trait

firmness and trait both are nouns.

Word	Noun	Adjective	Verb	Adverb
firmness	Yes	No	No	No
trait	Yes	No	No	No

As nouns, trait is a hypernym of firmness; that is, trait is a word with a broader meaning than firmness:

firmness (noun)	trait (noun)
the quality of being steady or securely and immovably fixed in place	a distinguishing feature of your personal nature
the trait of being resolute
the property of being unyielding to the touch
the muscle tone of healthy tissue