Nitrile Rubber Definition - Nitrile rubber is a synthetic rubber made from a copolymer of acrylonitrile and butadiene. It has good elastomeric... Nitrile Rubber Definition - Nitrile rubber is a synthetic rubber made from a copolymer of acrylonitrile and butadiene. It has good elastomeric properties and is also resistant to physical hazards like punctures, cuts, snags, abrasion, oil, caustics and aliphatic hydrocarbons. As a result of its strength and resiliency, it is used in several saftety-related applications.