LD-50

**Semantic type:** Quantitative Concept

**Definition:** The dose of a chemical or biologic preparation (e.g., a bacterial exotoxin or a suspension of bacteria) that is likely to cause death in 50% of the animals being tested; it varies in relation to the type of animal and the route of administration; (the absolute lethal dose is LD100, and minimal lethal dose is LD05).

**Synonyms:** - LC-50 - LC50 - LD50 - Lethal Dose - 50% - Median Lethal Dose