General English


  • Chemical term for an element or compound which speeds a reaction but is itself left unaltered when the process is complete. Catalysis is encountered – e.g. – in reactions in planetary atmospheres and in nucleosynthesis in stars, as in the carbon cycle.

Cars & Driving

  • noun a substance that changes the rate of a chemical reaction without itself being used up; in a catalytic converter the element which reduces the toxicity of the exhaust gases
  • noun a special agent added to a plastic body filler or resin or two-pack paint to speed up the setting process of the basic material applied


  • The hardener that accelerates the curing of adhesives, such as synthetic resins.


  • A substance that accelerates a chemical reaction significantly, and which is not itself consumed in the process. By the end of the reaction, a catalyst is returned to its original state. An example is the platinum utilized in a fuel cell.
  • Any agent which speeds up a process significantly.


  • noun a substance that produces or helps a chemical reaction without itself changing