8 letters · 8 points in Scrabble
adjective showing sustained enthusiastic action with unflagging vitality
adjective characterized by hard work and perseverance
originEtymology tree English tire 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 tireless From tire (“to become sleepy or weary”) + -less.
Etymology from Wiktionary, CC BY-SA 3.0