Effluvium

[Sarah]

Subtile or invisible emanation; exhalation perceived by thesense of smell; especially, noisome or noxious exhalation; as, theeffluvium from diseased or putrefying bodies, or from ill drainage.

[Sarah]

(ĭ-flo͞oˈvē-əm)
noun pl. effluvia ef·flu·vi·a (-vē-ə) or ef·flu·vi·ums
A usually invisible emanation or exhalation, as of vapor or gas.
a. A byproduct or residue; waste.
b. The odorous fumes given off by waste or decaying matter.
An impalpable emanation; an aura.

[Sarah]

A dissagreable or offensive smell.

[Sarah]

1: an invisible emanation; especially : an offensive exhalation or smell
2: a by-product especially in the form of waste