emission n.

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.