grimness vs asperity

grimness and asperity both are nouns.

Word	Noun	Adjective	Verb	Adverb
grimness	Yes	No	No	No
asperity	Yes	No	No	No

As nouns, grimness and asperity are synonyms defined as:

Other synonyms of grimness include hardship, rigor, rigorousness, rigour, rigourousness, severeness, severity.

grimness (noun)	asperity (noun)
something hard to endure	something hard to endure
the quality of being ghastly	harshness of manner