"one who contends with another," 1590s, from French antagoniste (16c.) or directly from Late Latin antagonista, from Greek antagonistēs "competitor, opponent, rival," agent noun from antagonizesthai "to struggle against, oppose, be a rival," from anti "against" (see anti-) + agonizesthai "to contend for a prize," from agon "a struggle, a contest" (see agony). Originally in battle or sport, extended 1620s to any sphere of human activity.
late 14c., narcotik, "substance which directly induces sleep or allays sensibility and blunts the senses," from Old French narcotique (early 14c.), noun use of adjective, and directly from Medieval Latin narcoticum, from Greek narkōtikon, neuter of narkōtikos "making stiff or numb," from narkōtos, verbal adjective of narkoun "to benumb, make unconscious," from narkē "numbness, deadness, stupor, cramp" (also "the electric ray").
This has been connected to a PIE root *(s)nerq- "to turn, twist," with cognates in Germanic (Old Norse snara "to turn, swing, wind;" see snare (n.1)), but Beekes finds this "semantically far from convincing," and writes, "The structure of this word looks non-IE. Therefore, we should rather assume a Pre-Greek word *nark-." Sense of "any illegal drug" first recorded 1926, American English. Related: Narcotics.
c. 1600, "having the power to produce stupor," from French narcotique (14c.) or German narkotisch and directly from Medieval Latin narcoticus, from Greek narkōtikos (see narcotic (n.)). As "consisting in or characterized by stupor," from 1660s. Related: Narcotical (1580s).
1690s, "state of unconsciousness caused by a narcotic," Modern Latin, from Greek narkōsis, from narkoun "to benumb" (see narcotic (n.)).
"marijuana, Cannabis sativa smoked as a narcotic," 1660s, from Afrikaans, from Khoisan (Hottentot) dachab. Originally the name of an indigenous plant used as a narcotic, extended to marijuana by 1796.