plural effluvia. [Latin from effluo, to flow out. See Flow .] The minute and often invisible particles which exhale from most, if not all terrestrial bodies, such as the odor or smell of plants, and the noxious exhalations from diseased bodies or putrefying animal or vegetable substances.

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.