depressant
de-pres-sant
noun
A substance, especially a drug, that reduces physiological or nervous activity.
"Alcohol is a common central nervous system depressant."
Thesaurus
Synonyms: narcotizing, sedative, ataraxic, tranquillizing, tranquilising, tranquilizing, tranquillising, hypnogogic, narcotising, hypnagogic, soporific, relaxant
Antonyms: stimulative