An emission is something that's been released or emitted into the world. Car exhaust, burps, and radio broadcasts are all examples of emissions.

Technically, an emission is anything that's been released out into the open. But more often it refers to gases being released into the air, like greenhouse gasses or emissions from power plants and factories. Anytime your body emits something (sweat, drool, gas), it's also considered an emission. Be careful not to confuse this word with the closely spelled omission — that's something that's been left out.

Definitions of emission
  1. noun
    the act of emitting; causing to flow forth
    synonyms: emanation
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    the act of spreading outward from a central source
    discharge, venting
    the act of venting
    the act (or an instance) of subjecting a body or substance to the impact of high-energy particles (as electrons or alpha rays)
    type of:
    egress, egression, emergence
    the act of coming (or going) out; becoming apparent
  2. noun
    a substance that is emitted or released
    synonyms: discharge
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    exudate, exudation
    a substance that oozes out from plant pores
    transudate, transudation
    a substance that transudes
    a foul-smelling outflow or vapor (especially a gaseous waste)
    a watery discharge from the mucous membranes (especially from the eyes or nose)
    vaginal discharge
    discharge of secretions from the cervical glands of the vagina; normally clear or white
    any of various substances (soluble in water) that exude from certain plants; they are gelatinous when moist but harden on drying
    a milky exudate from certain plants that coagulates on exposure to air
    type of:
    material, stuff
    the tangible substance that goes into the makeup of a physical object
  3. noun
    any of several bodily processes by which substances go out of the body
    synonyms: discharge, expelling
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    elimination, evacuation, excreting, excretion, voiding
    the bodily process of discharging waste matter
    catamenia, flow, menses, menstruation, menstruum, period
    the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause
    incontinence, incontinency
    involuntary urination or defecation
    hypermenorrhea, menorrhagia
    abnormally heavy or prolonged menstruation; can be a symptom of uterine tumors and can lead to anemia if prolonged
    micturition, urination
    the discharge of urine
    abnormally light or infrequent menstruation
    type of:
    activity, bodily function, bodily process, body process
    an organic process that takes place in the body
  4. noun
    the occurrence of a flow of water (as from a pipe)
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    type of:
    flow, flowing
    the motion characteristic of fluids (liquids or gases)
  5. noun
    the release of electrons from parent atoms
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    an emission of photoelectrons (especially from a metallic surface)
    field emission
    the emission of electrons that are stripped from parent atoms by a high electric field
    photoelectric emission
    the release or absorption of quanta above a certain energy level
    radiation, radioactivity
    the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay
    secondary emission
    the emission of electrons from a surface that is bombarded by higher energy primary electrons
    thermal emission, thermionic emission
    the emission of electrons from very hot substances
    corpuscular radiation, particulate radiation
    a stream of atomic or subatomic particles that may be charged positively (e.g. alpha particles) or negatively (e.g. beta particles) or not at all (e.g. neutrons)
    type of:
    a process that liberates or discharges something
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