Ef·flu·vi·um n.; pl. Effluvia   Subtile or invisible emanation; exhalation perceived by the sense of smell; especially, noisome or noxious exhalation; as, the effluvium from diseased or putrefying bodies, or from ill drainage.
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  effluvium
       n : a foul-smelling outflow or vapor (especially a gaseous
           waste)
       [also: effluvia (pl)]