Synonyms for Sedative (same or very similar meaning)
WordNet sense 1 (a drug that reduces excitability and calms a person):
downer, sedative drug
WordNet sense 2 (tending to soothe or tranquilize):
ataractic, ataraxic, tranquilising, tranquilizing
WordNet sense 3 (capable of depressing physiological or psychological activity or response by a chemical agent):
depressant
From the ODE community, based on WordNet
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