emission

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act or an instance of emitting.
• noun Something emitted.
• noun A substance discharged into the air, especially by an internal combustion engine.

from The Century Dictionary.

• noun 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.
• noun That which is emitted, or sent or thrown out.
• noun 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.
• noun In physiology, a discharge, especially an involuntary discharge, of semen.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act of sending or throwing out; the act of sending forth or putting into circulation; issue
• noun That which is sent out, issued, or put in circulation at one time; issue.
• noun (Physics) the theory of Newton, regarding light as consisting of emitted particles or corpuscles. See Corpuscular theory, under Corpuscular.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun That which is emitted or sent out.
• noun The act of sending or throwing out; the act of sending forth or putting into circulation; issue.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the occurrence of a flow of water (as from a pipe)
• noun the act of emitting; causing to flow forth
• noun the release of electrons from parent atoms
• noun any of several bodily processes by which substances go out of the body
• noun a substance that is emitted or released