untiring

from WordNet (r) 3.0 (2006)

untiring
    adj 1: characterized by hard work and perseverance [syn:
           {hardworking}, {industrious}, {tireless}, {untiring}]

from The Collaborative International Dictionary of English v.0.48

Untiring \Untiring\
   See {tiring}.

from Moby Thesaurus II by Grady Ward, 1.0

90 Moby Thesaurus words for "untiring":
      assiduous, cartilaginous, chewy, cohesive, constant, continuing,
      coriaceous, dedicated, determined, diligent, dogged, durable,
      enduring, faithful, fibrous, gristly, hard, hardy, immutable,
      inalterable, indefatigable, indomitable, industrious,
      inexhaustible, insistent, invincible, lasting, leatherlike,
      leathery, loyal, never-tiring, obstinate, patient, patient as Job,
      permanent, perseverant, persevering, persistent, persisting,
      pertinacious, plodding, plugging, preoccupied, rapt, relentless,
      resistant, resolute, ropy, sedulous, sinewy, single-minded,
      sleepless, slogging, stable, steadfast, steady, stiff, stringy,
      strong, stubborn, tenacious, tireless, tough, tough as leather,
      unabating, unconquerable, undaunted, undiscouraged, undrooping,
      unfailing, unfaltering, unflagging, unflinching, unintermitting,
      uninterrupted, unnodding, unrelaxing, unrelenting, unremitting,
      unsleeping, unswerving, unwavering, unwearied, unwearying,
      unwinking, utterly attentive, vigorous, viscid, weariless, wiry