GRIMNESS
asperity, grimness, hardship, rigor, rigour, severity, severeness, rigorousness, rigourousness
(noun) something hard to endure; “the asperity of northern winters”
ghastliness, grimness, gruesomeness, luridness
(noun) the quality of being ghastly
Source: WordNet® 3.1
Etymology
Noun
grimness (usually uncountable, plural grimnesses)
The characteristic or quality of being grim.
Source: Wiktionary
Grim"ness, n. Etym: [AS. grimnes.]
Definition: Fierceness of look; sternness; crabbedness; forbiddingness.
Source: Webster’s Unabridged Dictionary 1913 Edition