Definition of: indefatigable

(in′də·fat′ə·gə·bəl) adjective
Not yielding readily to fatigue; tireless; unflagging. [<MF indéfatigable <L indefatigabilis <in-not + defatigare tire out]
—in′de·fat′i·ga·bil′·i·ty, in′de·fat′i·ga·ble·ness noun
—in′de·fat′i·ga·bly adverb Synonyms: assiduous, indomitable, industrious, never–failing, never–tiring, persevering, persistent, tireless, unfailing, unfaltering, unflagging, untiring, unwearied. Antonyms: defeated, despondent, discouraged, fainting, faltering, flagging, indolent, negligent, remiss, wearied.