Retarder may refer to:
Retarder (album), an album by The Unband Retarder (chemistry), a chemical agent that slows down a chemical reaction Retarder (mechanical engineering), a device for slowing down large trucks, lorries, buses, coaches and other vehicles Retarder (railroad), a device to slow railroad freight cars as they are sorted into trains Acrylic retarder, a chemical agent added to fine art acrylic paint to slow its short drying time Dough retarder, a refrigerator used to slow down proofing of yeast when making dough Film-type patterned retarder, a technology promoted by LG that is employed in its line of 3D televisions based on circular polarization Retardation plate, an optical device that alters the polarization state of a light wave traveling through it A component in weapons that slow down their rate of fire
See also Retardation (disambiguation)