Synonyms of grueling

1 Syllable
hard, stiff, harsh, trying
2 Syllables
heavy, racking, brutal, hairy, fierce, strenuous, grinding, arduous, tiring, crushing
3 Syllables
laborious, punishing, demanding, torturous, exhausting, severe, backbreaking, fatiguing, onerous, chastening
4 Syllables
excruciating, overtaxing
5 Syllables
torturesome