- indefatigable, tireless, unflagging, unwearying - showing sustained enthusiastic action with unflagging vitality; "an indefatigable advocate of equal rights"; "a tireless worker"; "unflagging pursuit of excellence"
Antonyms: lethargic, unergetic (indirect, via energetic)
- hardworking, industrious, tireless, untiring - characterized by hard work and perseverance
Antonym: negligent (indirect, via diligent)