Adjective relentless has 2 senses
- grim, inexorable, relentless, stern, unappeasable, unforgiving, unrelenting - 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"
Antonym: placable (indirect, via implacable)
- persistent, relentless, unrelenting - never-ceasing; "the relentless beat of the drums"
Antonym: sporadic (indirect, via continual)
,