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
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Helmenstine, Anne Marie, Ph.D. "Inhibitor Definition in Chemistry." ThoughtCo, Aug. 28, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 28). Inhibitor Definition in Chemistry. Retrieved from Helmenstine, Anne Marie, Ph.D. "Inhibitor Definition in Chemistry." ThoughtCo. (accessed January 30, 2023).