relentless relentless /rɪˈlɛntlɪs/

adjective

1. () Not to be placated, appeased or moved by entreaty  ( unappeasable , unforgiving , unrelenting , grim , inexorable , relentless , stern )
   not to be placated, appeased or moved by entreaty
    Grim determination
   grim determination
    Grim necessity
   grim necessity
    Russia's final hour, it seemed, approached with inexorable certainty
   Russia's final hour, it seemed, approached with inexorable certainty
    Relentless persecution
   relentless persecution
    The stern demands of parenthood
   the stern demands of parenthood
   
2. () Never-ceasing  ( unrelenting , relentless , persistent )
   never-ceasing
    The relentless beat of the drums
   the relentless beat of the drums