depressant /dɪˈpɹɛsənt/noun 2adjective 1forms 3 noun2 •A pharmacological substance which decreases neuronal or physiological activity.Alcohol acts first as a stimulant and then as a depressant. •An agent that inhibits the flotation of a mineral or minerals. adjective1 •Reducing functional or nervous activity. formsdepressants · more depressant · most depressant