Noun
One who, or that which, retards.
Source: Webster's dictionaryAn accelerator speeds up the cure reaction, while a retarder delays it. Source: Internet
A waveplate or retarder is an optical device that alters the polarization state of a light wave travelling through it. Source: Internet
Highly effective foam retarder for water borne coating systems based on polymer emulsions, alkyd emulsions or hybrid systems. Source: Internet
If you use them as if they were oils and you were an impressionist, you can do the alla prima, impressionist thing, and complete your painting with a single layer, although you might have to use an acrylic retarder to do so. Source: Internet
The fuze for a retarded bomb requires that the retarder be open a minimum time to ensure safe separation. Source: Internet