Concentration of a substance that causes a defined inhibition of a given system: IC 50 is the median concentration that causes 50% inhibition.
See also: lethal concentration
Source:
PAC, 1993, 65, 2003. 'Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)' on page 2060 (https://doi.org/10.1351/pac199365092003)