n. The act of emitting, or of sending or throwing out; a putting forth or issuing: as, the emission of light from the sun or other luminous body; the emission of steam from a boiler; the emission of paper money.n. That which is emitted, or sent or thrown out.n. Specifically— In finance, an amount or quantity of any representative of value issued or put into circulation; an issue: as, the entire emission (of coin, bank-notes, or the like) has been called in or redeemed; the first, second and third emissions of United States notes issued during the civil war.n. In physiology, a discharge, especially an involuntary discharge, of semen.