Isoprene \I"so*prene\, n. [Etymol. uncertain.] (Chem.)
An oily, volatile unsaturated hydrocarbon ({C5H8}), obtained
by the distillation of caoutchouc or gutta-percha, and used
to make synthetic rubber by polymerization. In organic
chemistry, it is viewed conceptually as the building block of
the terpene series of hydrocarbons.
[1913 Webster +PJC]