synthetic rubber

:  any of various products (such as GR-S, neoprene, butyl rubber, or nitrile rubber) that resemble natural rubber more or less closely especially in physical properties and ability to be vulcanized, that are made usually by polymerization of butadiene, isoprene, or similar unsaturated hydrocarbons or by copolymerization of such hydrocarbons with styrene, isobutylene, acrylonitrile, or other polymerizable compounds, and that have uses similar to those of natural rubber but are superior for some applications and inferior for others and are often used in combination with natural rubber :  rubber 2b — compare elastomer