nounpl. -·mas or -·mata
- a vapor rising as from marshes or decomposing animal or vegetable matter: formerly supposed to poison and infect the air, causing malaria, etc.
- an unwholesome or befogging atmosphere, influence, etc.
Origin of miasmaModern Latin from Gr, pollution from miainein, to pollute from Indo-European base an unverified form mai- from source Old English mal, a spot