Acrylonitrile butadiene styrene (ABS) (chemical formula (C8H8)x· (C4H6)y·(C3H3N)z) is a common thermoplastic polymer. Its glass transition temperature is approximately 105 °C (221 °F).ABS is amorphous and therefore has no true melting point.

ABS's light weight and ability to be injection molded and extruded make it useful in manufacturing products such as drain-waste-vent (DWV) pipe systems, musical instruments (recorders, plastic clarinets, and piano movements), golf club heads (because of its good shock absorbance), automotive trim components, automotive bumper bars, medical devices for blood access, enclosures for electrical and electronic assemblies, protective headgear, whitewater canoes, buffer edging for furniture and joinery panels, luggage and protective carrying cases, small kitchen appliances, and toys, including Lego and Kre-O bricks. Household and consumer goods are the major applications of ABS. Keyboard keycaps are commonly made out of ABS.