median lethal dose

American  

noun

1. the quantity of a lethal substance, as a poison or pathogen, or of ionizing radiation that will kill 50 percent of the organisms subjected to it in a specified time period. LD 5 0

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median lethal dose British  

noun

1. the amount of a drug or other substance that, when administered to a group of experimental animals, will kill 50 per cent of the group in a specified time

2. the amount of ionizing radiation that will kill 50 per cent of a population in a specified time

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Etymology

Origin of median lethal dose

First recorded in 1945–50

Example Sentences

In toxicology, the median lethal dose, or LD50, is the approximate dose required to kill half the animals in a population being studied.

From Salon