MERCILESS

adj. cruel, pitiless, ruthless, heartless, unmerciful, inhumane, inhuman, brutal, savage, barbarous, barbaric, barbarian, crude, rude, rough, harsh, tough, callous, hard, hard-hearted, illiberal, tyrannical, stony-hearted, cold, severe, unsparing, insensitive, indifferent, unsympathetic, unforgiving, ungracious, malevolent, thoughtless, uncharitable, inconsiderate, unmoved, unbending, inflexible, relentless, unrelenting, inexorable Their captors proved to be utterly merciless The merciless sun beat down on the desert outpost.