The Collaborative International Dictionary of English v.0.48:

Indefinitely \In*def"i*nite*ly\, adv.
   In an indefinite manner or degree; without any settled
   limitation; vaguely; not with certainty or exactness; as, to
   use a word indefinitely.
   [1913 Webster]

         If the world be indefinitely extended, that is, so far
         as no human intellect can fancy any bound of it. --Ray.
   [1913 Webster]

WordNet (r) 3.0 (2006):

indefinitely
    adv 1: to an indefinite extent; for an indefinite time; "this
           could go on indefinitely"