10 letters · 10 points in Scrabble
adjective not to be placated or appeased or moved by entreaty
adjective never-ceasing
originEtymology tree English relent Proto-Indo-European *lewh₁- Proto-Indo-European *lewHs-der. Proto-Germanic *leusaną Proto-Germanic *lausaz Proto-Germanic *-lausaz Proto-West Germanic *-laus Old English -lēas Middle English -les English -less English relentless From relent + -less.
Etymology from Wiktionary, CC BY-SA 3.0