DEPRESSANT
depressant
(adjective) capable of depressing physiological or psychological activity or response by a chemical agent
sedative, sedative drug, depressant, downer
(noun) a drug that reduces excitability and calms a person
Source: WordNet® 3.1
Etymology
Noun
depressant (countable and uncountable, plural depressants)
(pharmaceutical drug) A pharmacological substance which decreases neuronal or physiological activity.
(mining) An agent that inhibits the flotation of a mineral or minerals.
Adjective
depressant (comparative more depressant, superlative most depressant)
(pharmaceutical effect) reducing functional or nervous activity.
Source: Wiktionary
De*press"ant, n. (Med.)
Definition: An agent or remedy which lowers the vital powers.
Source: Webster’s Unabridged Dictionary 1913 Edition