Malaria \Ma*la"ri*a\, n. [It., contr. fr. malaaria bad air. See Malice, and Air.]

1. Air infected with some noxious substance capable of engendering disease; esp., an unhealthy exhalation from certain soils, as marshy or wet lands, producing fevers; miasma.

Note: The morbific agent in malaria is supposed by some to be a vegetable microbe or its spores, and by others to be a very minute animal blood parasite (an infusorian).

2. (Med.) A morbid condition produced by exhalations from decaying vegetable matter in contact with moisture, giving rise to fever and ague and many other symptoms characterized by their tendency to recur at definite and usually uniform intervals.

Source: Webster's Revised Unabridged Dictionary (1913)