- any of several substances similar to natural rubber in properties and uses, produced by the polymerization of an unsaturated hydrocarbon, as butylene or isoprene, or by the copolymerization of such hydrocarbons with styrene, butadiene, or the like.
- any of various synthetic materials, similar to natural rubber, made by polymerizing unsaturated hydrocarbons, such as isoprene and butadiene
