The Collaborative International Dictionary of English v.0.48:

Par'a rubber \Par['a] rubber\
   The caoutchouc obtained from the South American
   euphorbiaceous tree Hevea brasiliensis, hence called the
   Par['a] rubber tree, from the Brazilian river and seaport
   named Par['a]; also, the similar product of other species of
   Hevea. It is usually exported in flat round cakes, and is a
   chief variety of commercial India rubber.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Para rubber
    n 1: a type of natural rubber obtained from tropical South
         American trees