incurably

from WordNet (r) 3.0 (2006)

incurably
    adv 1: to an incurable degree; "she was incurably optimistic"
    2: in a manner impossible to cure; "he is incurably ill"

from The Collaborative International Dictionary of English v.0.48

Incurably \In*cur"a*bly\, adv.
   In a manner that renders cure impracticable or impossible;
   irremediably. "Incurably diseased." --Bp. Hall. "Incurably
   wicked." --Blair.
   [1913 Webster]