difficult, hard, challenging, laborious, arduous, backbreaking, killer, murderous, grueling, gruelling (UK), strenuous, demanding, heavy, rigorous, harsh, rough, severe, brutal, hard going (informal), a struggle

Synonyms for TOUGH: strong, robust, hardy, stalwart, wiry, stout, ruffianly, mighty, sturdy, robust; Antonyms for TOUGH: weak, fragile, wobbly, unstable, delicate, vulnerable, tender, easy, facile, controllable.

Thesaurus: synonyms, antonyms, and examples strict Her parents were very strict. firm I was always very firm with my children. take a hard line on The school takes a hard line on bullying. authoritarian The country was under the rule of an authoritarian leader. stringent Stringent safety regulations were introduced after the accident.

tough Synonyms: resistent, stubborn, lentous, fibrous, difficult, refractory, hard, unmanageable, tenacious, firm, strong