foam rubber - spongy rubber; made by introducing air bubbles before vulcanization

latex - a milky exudate from certain plants that coagulates on exposure to air

crepe rubber - crude natural rubber; used mainly for shoe soles

synthetic rubber - any of various synthetic materials that resemble rubber

cold rubber - a rubber made at low temperatures (5 degrees Centigrade) which is tougher than conventional rubber and is often used in car tires

ebonite, hard rubber, vulcanite - a hard nonresilient rubber formed by vulcanizing natural rubber

para rubber - a type of South American rubber