tireless
adjective
- untiring/indefatigable
Wiktionary
adj
Etymology: Etymology 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 + -less.
- Without a tire (wheel covering); tyreless.