tranquillizer(n = noun.artifact) antianxiety agent, ataractic, ataractic agent, ataractic drug, tranquilizer, tranquilliser - a drug used to reduce stress or tension without reducing mental clarity;
is a kind of psychotropic agent, sedative-hypnotic, sedative-hypnotic drug
has particulars: antipsychotic, antipsychotic agent, antipsychotic drug, major tranquilizer, major tranquilliser, major tranquillizer, neuroleptic, neuroleptic agent, neuroleptic drug, antianxiety drug, anxiolytic, anxiolytic drug, minor tranquilizer, minor tranquilliser, minor tranquillizer
Derived form verb tranquillize2
One who, or that which, tranquilizes. [1913 Webster]
tranquillizer, n. (US tranquilizer, -iser) a drug used to diminish anxiety.