international unit

noun Pharmacology.

an internationally agreed upon standard, as measured by bioassay, to which samples of a substance, as a drug or hormone, are compared to ascertain their relative potency.
the particular quantity of such a substance, which causes a specific biological effect. Abbreviation: IU

Nearby words

  1. international telecommunications satellite organization,
  2. international telecommunications union,
  3. international telegram,
  4. international temperature scale,
  5. international trade commission, united states,
  6. international workingmen's association,
  7. internationale,
  8. internationalisation,
  9. internationalism,
  10. internationalist

Origin of international unit

First recorded in 1920–25 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Medicine definitions for international unit

international unit


The quantity of a biologically active substance, such as a hormone or vitamin, required to produce a specific response.
A unit of potency for similarly active substances, based on this quantity and accepted as an international standard.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for international unit

international unit

A unit for measuring a biologically active substance, such as a hormone or vitamin.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.