median lethal dose, \(\textrm{LD}_{50}\)

https://doi.org/10.1351/goldbook.M03810
Statistically derived @DT07361@ of a chemical or physical agent (radiation) expected to kill 50% of organisms in a given population under a defined set of conditions.
Source:
PAC, 1993, 65, 2003. (Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)) on page 2068 [Terms] [Paper]