barbiturate (bar-bit-yoor-ăt) n. any of a group of drugs, derived from barbituric acid, that depress activity of the central nervous system. Because barbiturates produce psychological and physical dependence and have serious toxic side-effects (see barbiturism), their use has declined. See amobarbital, butobarbital, phenobarbital, thiopental.

bar·bi·tu·rate / bärˈbichərit; -əˌrāt/ • n. any of a class of sedative and sleep-inducing drugs derived from barbituric acid. ∎ Chem. a salt or ester of barbituric acid.

barbiturate Any one of a group of drugs derived from barbituric acid, which have a depressant effect on the central nervous system. Barbiturates were originally used as sedatives and sleeping pills but their clinical use is now limited due to their toxic side-effects; prolonged use can lead to addiction. Specific barbiturates in clinical use include butobarbital, used to treat insomnia, and thiopental, used as an anaesthetic.

barbiturate Drug used as a sedative or to induce sleep. Highly addictive and dangerous in high doses, or in combination with other drugs such as alcohol or tranquillizers, most barbiturates are no longer prescribed. Short-acting barbiturates are used in surgery to induce general anaesthesia; long-acting formulations are prescribed for epilepsy.