†(a) rubber made by subjecting the natural material to certain chemical or physical processes (obsolete. rare); (b) = synthetic rubber n. at synthetic…

any of various synthetic materials, typically polymeric hydrocarbons, having some properties of natural rubber.

Originally: India rubber, caoutchouc, esp. as used for erasing pencil marks. In later use more widely: any of a large range of polymeric organic…

Any of various rubbers (esp. synthetic ones) or plastic substances resembling rubber.