... syn: miasma, miasm] Merriam Webster's noun (plural -mas; also miasmata) Etymology: New Latin, from Greek, defilement, from miainein to pollute ... adjective • miasmic adjective • miasmically adverb Oxford Reference Dictionary n. (pl. miasmata or miasmas) archaic an infectious or noxious vapour. Derivatives: miasmal ... Webster's 1913 Dictionary Miasma Mi*as"ma, n.; pl. Miasmata. [NL., fr. Gr. ? defilement, fr. ? to pollute.] Infectious particles or ...