What's the adjective for hardinesses? Here's the word you're looking for.
Included below are past participle and present participle forms for the
verbs harden and hardship which may be used as adjectives within certain contexts.
hard
(of material or fluid) Having a severe property; presenting difficulty.
“This was produced by the Department for International Development, the fief of Clare Short, once a totemic figure for the hardish left.”
“I polish my pots with a tumbled agate or back of a spoon when the pots are on the hardish side of leather hard and get a nice shine which carries through even after firing.”
“All plant rough from hardish hairs covering it.”
hardy
Having rugged physical strength; inured to fatigue or hardships. A hardy plant is one that can withstand the extremes of climate, such as frost.