Infectious particles or germs floating in the air; air made noxious by the presence of such particles or germs; noxious effluvia; malaria.
- A noxious atmosphere or influence: "The family affection, the family expectations, seemed to permeate the atmosphere . . . like a coiling miasma” ( Louis Auchincloss).
- A poisonous atmosphere formerly thought to rise from swamps and putrid matter and cause disease.
- A thick vaporous atmosphere or emanation: wreathed in a miasma of cigarette smoke.