showing sustained enthusiastic action with unflagging vitality; "an indefatigable advocate of equal rights"; "a tireless worker"; "unflagging pursuit of excellence"
not capable of being conquered or vanquished or overcome; "a tribute to his courage...and his unconquerable will"- R.E.Danielson; "faced unconquerable difficulties"
stubbornly unyielding; "dogged persistence"; "dour determination"; "the most vocal and pertinacious of all the critics"; "a mind not gifted to discover truth but tenacious to hold it"- T.S.Eliot; "men tenacious of opinion"
characterized by care and perseverance in carrying out tasks; "a diligent detective investigates all clues"; "a diligent search of the files"
quietly and steadily persevering especially in detail or exactness; "a diligent (or patient) worker"; "with persevering (or patient) industry she revived the failing business"