Synonyms of punishing

1 Syllable
hard
2 Syllables
grueling, brutal, taxing, penal, hitting, arduous, whacking
3 Syllables
torturous, backbreaking
4 Syllables
unabated, excruciating, punitive, correctional
5 Syllables
retributive, torturesome, retaliatory, retaliative, disciplinary