Source : Webster's Revised Unabridged Dictionary (1913)

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.