say it: mee-AZ-muh
miasma is a noun meaning "an unwholesome atmosphere". It carries 2 recorded senses.
unhealthy vapors rising from the ground or other sources
“the miasma of the marshes”
“a miasma of cigar smoke”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for miasma come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.