Indefatigable

a.

1.

Incapable of being fatigued; not readily exhausted; unremitting in labor or effort; untiring; unwearying; not yielding to fatigue; as, indefatigable exertions, perseverance, application. Upborne with indefatigable wings. - Milton.

Adj.

1.

indefatigable - showing sustained enthusiastic action with unflagging vitality; "an indefatigable advocate of equal rights"; "a tireless worker"; "unflagging pursuit of excellence" Synonyms: tireless, unflagging, unwearying

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