名詞 depressant:

1. a drug that reduces excitability and calms a person
   同義詞：sedative, sedative drug, downer

形容詞 depressant:

1. capable of depressing physiological or psychological activity or response by a chemical agent

1. Any of various depressant drugs used to reduce tension or anxiety and to treat psychotic states.
   安定藥鎮(zhèn)定性藥物，用來減輕緊張狀態(tài)或焦慮并治療精神病癥

de.pres.sant

adj.（形容詞）
Tending to lower the rate of vital physiological activities.
抑制性的：降低重要生理活動(dòng)的速度的
n.（名詞）
An agent, especially a drug, that decreases the rate of vital physiological activities.
抑制劑：一種降低重要生理活動(dòng)速度的物質(zhì)（尤指藥品）