· not to be placated or appeased or moved by entreaty; "grim determination"; "grim necessity"; "Russia's final hour, it seemed, approached with inexorable certainty"; "relentless persecution"; "the stern demands of parenthood"
Synonym(s): grim, inexorable, relentless, stern, unappeasable, unforgiving
· punishingly harsh; "the brutal summer sun"; "a brutal winter"
Synonym(s): brutal
· never-ceasing; "the relentless beat of the drums"
Synonym(s): persistent, relentless