adjective
cruel, merciless
Synonyms: adamant, bound, bound and determined, dead set on, determined, dogged, ferocious, fierce, go for broke, grim, hang in, hang-tough, hard, harsh, implacable, inexorable, inflexible, inhuman, mortal, obdurate, pitiless, remorseless, rigid, rigorous, ruthless, single-minded, stiff, stop at nothing, strict, stringent, unappeasable, unbending, uncompromising, undeviating, unflinching, unforgiving, unrelenting, unstoppable, unyielding, vindictive
Antonyms: kind, merciful, sympathetic, understanding
adjective
continuous, neverending
Synonyms: incessant, nonstop, persistent, pertinacious, punishing, sustained, tenacious, unabated, unbroken, unfaltering, unflagging, unrelenting, unrelieved, unremitting, unstoppable
Antonyms: ending, intermittent, stopping