noun pl. miasmas -·mas or miasmata -·mata (-mə tə)

1. a vapor rising as from marshes or decomposing animal or vegetable matter, formerly supposed to poison and infect the air, causing malaria, etc.
2. an unwholesome or befogging atmosphere, influence, etc.

Etymology: ModL < Gr, pollution < miainein, to pollute < IE base *mai- > OE mal, a spot