The Collaborative International Dictionary of English v.0.48:

Unwearied \Un*wea"ried\, a.
   Not wearied; not fatigued or tired; hence, persistent; not
   tiring or wearying; indefatigable. -- Un*wea"ried*ly, adv.
   -- Un*wea"ried*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unwearied
    adj 1: with unreduced energy [syn: untired, unwearied,
           unweary]

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "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, untired, untiring,
   unwavering, unwearying, unwinking, utterly attentive, vehement,
   weariless, zealous