What is a synonym for "robustness"?

Common synonyms include: activity, animation, ardor, aythya, brawn, brawniness.

Robustness

noun

noun ·3 syllables ·Moderate ·College level

Noun

1
The quality of being robust. countable, uncountable
"Robustness was considered to be an essential feature because of the comparatively high starting effort and the generally rough work for which the locomotives are to be used."
2
the characteristic of being strong enough to withstand intellectual challenge wordnet
3
the property of being strong and healthy in constitution wordnet

"Graceful degradation is a close second to robustness."

From robust + -ness.