relentless (adjective) relentless: cruel, merciless
Sinonime: 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,
vindictiveAntonime: kind,
merciful,
sympathetic,
understanding