Plastics are a wide range of synthetic or semisynthetic materials composed primarily of polymers. Their defining characteristic, plasticity, allows them to be molded, extruded, or pressed into a diverse range of solid forms.
plastic, polymeric material that has the capability of being molded or shaped, usually by the application of heat and pressure.
Plastic is a polymeric material —that is, a material whose molecules are very large, often resembling long chains made up of a seemingly endless series of interconnected links.