Narcotic
Narcotic (adj & noun) /nɑːˈkɒt.ɪk/ US /nɑːrˈkɑːţ-/
noun: an addictive drug from opium that relieves pain and causes dizziness, drug, medicine, tranquilizing – painkiller:
Adjective: interminable, tedious, boring, dull, monotonous, calming
The physician prescribed me some narcotic to deal with my acute pain.
Antonym: stimulant
Adverb: narcotically