chloral hydrate chlo·ral hydrate (klôr'əl)
n.
A crystalline compound used medicinally as a sedative and hypnotic.
the first synthetically produced sedative-hypnotic drug, commonly used in the late 19th century to treat insomnia and still occasionally used to reduce anxiety or produce sleep before surgery. Chloral hydrate acts as a depressant on the central nervous system, with sedative effects similar to those of barbiturates.