"person sent on a mission," 1620s, from French émissaire (17c.) or directly from Latin emissarius "a scout, a spy," literally "that is sent out," from emissus, past participle of emittere "send forth" (see emit).
early 15c., "something sent forth," from Old French émission (14c.) and directly from Latin emissionem (nominative emissio) "a sending out, a projecting, hurling, letting go, releasing," noun of action from past participle stem of emittere "send out" (see emit). Meaning "a giving off or emitting, the act of sending or throwing out" is from 1610s.
Middle English reken "to emit smoke," of smoke or stench, "to rise," from Old English recan (Anglian), reocan (West Saxon) "emit smoke," from Proto-Germanic *reukan (source also of Old Frisian reka "smoke," Middle Dutch roken, Dutch rieken "to smoke," Old High German riohhan "to smoke, steam," German rauchen "to smoke," riechen "to smell"); from the same source as the nouns (see reek (n.)).
Originally a strong verb, with past tense reac, past participle gereocen, but occasionally showing weak conjugation in Old English. Meaning "to emit a bad smell" is recorded from 1710 via sense "be heated and perspiring" (early 15c.). Related: Reeked; reeking.
"emit a short, sharp metallic sound," 1941, imitative. As a noun by 1971. Related: Plinked; plinking.