Inhibitor Definition in Chemistry

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In chemistry, an inhibitor is a substance that delays, slows or prevents a chemical reaction. It may also be called a negative catalyst.

Common Misspellings: inhibiter

There are three common classes of inhibitors:

  • Corrosion inhibitor: A corrosion inhibitor decreases the rate of oxidation of metal.
  • Enzyme inhibitor: In chemistry and biology, an enzyme inhibitor binds to an enzyme, lessening its activity. Enzyme inhibitors may be reversible or irreversible.
  • Reaction inhibitor: A reaction inhibitor is any substance that decreases the rate of a chemical reaction. Corrosion inhibitors and enzyme inhibitors are both types of reaction inhibitors. Reaction inhibitors are classified by their potency as strong, moderate, or weak.


  • Berg, J.; Tymoczko, J.; Stryer, L. (2002) Biochemistry. W. H. Freeman and Company. ISBN 0-7167-4955-6.
  • Center for Drug Evaluation and Research. "Drug Interactions & Labeling - Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers."
  • Gräfen, H.; Horn, E.-M.; Schlecker, H.; Schindler, H. (2002) "Corrosion." Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH: Weinheim. doi:10.1002/14356007.b01_08