* * *
LD50 or LD50 'el-'dē-'fif-tē n the amount of a toxic agent (as a poison, virus, or radiation) that is sufficient to kill 50 percent of a population of animals usu. within a certain time called also median lethal dose
* * *
the dose of a toxic compound that causes death in 50% of a group of experimental animals to which it is administered: used as a measure of the toxicity of drugs.
* * *
median lethal dose.Medical dictionary. 2011.