indefatigable indefatigable /ˌɪndɪˈfætɪgəbəl/

adjective

1. () Showing sustained enthusiastic action with unflagging vitality  ( unflagging , unwearying , indefatigable , tireless )
   showing sustained enthusiastic action with unflagging vitality
    An indefatigable advocate of equal rights
   an indefatigable advocate of equal rights
    A tireless worker
   a tireless worker
    Unflagging pursuit of excellence
   unflagging pursuit of excellence