miasma (n.) Look up miasma at Dictionary.com
1660s, from Modern Latin miasma "noxious vapors," from Greek miasma (genitive miasmatos) "stain, pollution, defilement, taint of guilt," from stem of miainein "to pollute," from possible PIE root *mai- (2) "to stain, soil, defile" (source of Old English mal "stain, mark," see mole (n.1)). Earlier form was miasm (1640s), from French miasme. Related: Miasmatic; miasmal.