The Collaborative International Dictionary of English v.0.48:
Caoutchouc \Caout"chouc\, n. [F. caoutchouc, from the South
A tenacious, elastic, gummy substance obtained from the milky
sap of several plants of tropical South America (esp. the
euphorbiaceous tree Siphonia elastica or Hevea
caoutchouc), Asia, and Africa. Being impermeable to liquids
and gases, and not readly affected by exposure to air, acids,
and alkalies, it is used, especially when vulcanized, for
many purposes in the arts and in manufactures. Also called
India rubber (because it was first brought from India, and
was formerly used chiefly for erasing pencil marks) and gum
elastic. See Vulcanization.
Mineral caoutchouc. See under Mineral.