hard

adjective

Requiring significant effort, skill, or endurance to achieve or understand.

"That was a very hard exam."

adverb

With great effort, force, or intensity; strenuously.

"She worked hard all day."

adjective

Solid, firm, or rigid; not easily broken, bent, or cut.

"The ground was hard after the frost."

Thesaurus

Synonyms: hard-boiled, steely, scheming, calculating, hardened, calculative, conniving, shrewd, case-hardened, intemperate, indulgent, heavy

Antonyms: diffuse, diffused, easy, lightly, soft, sonant, voiced