Nouns

(n)sedative, sedative drug, depressant, downera drug that reduces excitability and calms a person

Adjectives

(s)ataractic, ataraxic, sedative, tranquilizing, tranquillizing, tranquilising, tranquillisingtending to soothe or tranquilize“valium has a tranquilizing effect”, “took a hot drink with sedative properties before going to bed”