Tranquilizer

A tranquilizer refers to a drug which is designed for the treatment of anxiety, fear, tension, agitation, and disturbances of the mind, specifically to reduce states of anxiety and tension.
Tranquilizer, as a term, was first used by F.F. Yonkman (1953), from the conclusions of investigative studies using the drug reserpine, which showed the drug had a calming effect on all animals it was administered to. Reserpine is a centrally acting Rauwolfia alkaloid. The word directly refers to the state of tranquillity in a person and other animals.
The term is considered "popular" or "common", meaning it is not generally in use in the field of medicine. Specifically, it is used in reference to antipsychotic or neuroleptic medications.
The term is generally used as a synonym for sedative. When used by health care professionals, it is usually qualified or replaced with more precise terms:
Mood stabilizers might also be considered to belong to the classification of tranquilizing agents.