Meaning: Without regret or guilt. Never ending or improving (something unpleasant), relentless.
Synonyms: Heartless, pitiless, merciless, ruthless, callous, cruel, hard-hearted, inhumane, unmerciful, unforgiving, unfeeling, relentless, unabating, inexorable, unstoppable, unremitting.
Use: His behavior was remorseless after hearing his jail sentence.
Our friendship ended over his remorseless reaction to the tragic event.