tireless

• POS: Adjective
• HYPHEN: tire=less

CIDE DICTIONARY

tireless, a. 

 Untiring.  [1913 Webster]

OXFORD DICTIONARY

tireless, adj. having inexhaustible energy.

Derivative

tirelessly adv. tirelessness n.

THESAURUS

tireless

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