IPA: //ʌnˈtaɪərɪŋ//
KK: /ʌnˈtaɪərɪŋ/
Someone who does not get tired and continues to work hard without stopping, even when they are tired or frustrated.
Her untiring dedication to the project inspired everyone on the team.
Untiring → It is formed from "un-" (meaning not) and "tiring" (from the verb "tire", which comes from Old French *tirer*, meaning to pull or draw). The word "untiring" means not becoming fatigued or not losing energy.
Think of 'not' ('un-') becoming 'fatigued' ('tiring') — that's why untiring means someone who doesn't get tired.