difficultness
difficulty
strength
asperity
cheerlessness
crudity
durability
explosiveness
hardihood
harshness
imperiousness
inflexibility
insipidity
maintainability
massiveness
picturesqueness
robustness
roughness
savageness
slurring
sombreness
steadfastness
strangeness
toughness
uncouthness
unevenness
unwieldiness
wildness