Synonyms to untired

unwearied, ardent, assiduous, constant, continuing, diligent, dogged, enduring, energetic, faithful, fervent, hard, hardworking, immutable, inalterable, indefatigable, indomitable, industrious, insistent, invincible, laborious, lasting, loyal, never idle, never-tiring, obstinate, patient, patient as Job, permanent, perseverant, persevering, persistent, persisting, pertinacious, plodding, plugging, preoccupied, rapt, relentless, resolute, sedulous, single-minded, sleepless, slogging, stable, steadfast, steady, strenuous, stubborn, tenacious, tireless, unabating, unconquerable, undaunted, undiscouraged, undrooping, unexhausted, unfailing, unfaltering, unfatigued, unflagging, unflinching, unintermitting, uninterrupted, unnodding, unrelaxing, unrelenting, unremitting, unsleeping, unsparing, unswerving, untiring, unwavering, unwearying, unwinking, utterly attentive, vehement, weariless, zealous