miasma

noun

mi·​as·​ma mī-ˈaz-mə 

mē-

plural miasmas also miasmata mī-ˈaz-mə-tə 

mē-

1

: a vaporous exhalation formerly believed to cause disease

also : a heavy vaporous emanation (see emanation sense 2) or atmosphere

a miasma of tobacco smoke

2

: an influence or atmosphere that tends to deplete or corrupt

… freed from the miasma of poverty …

—Sir Arthur Bryant

the enervating miasma of fear

—The Times Literary Supplement (London)

also : an atmosphere that obscures : fog

miasmal

mī-ˈaz-məl 

mē-

adjective

miasmatic

ˌmī-əz-ˈma-tik 

mē-

adjective

miasmic

mī-ˈaz-mik 

mē-

adjective

miasmically

mī-ˈaz-mi-k(ə-)lē 

mē-

adverb

Did you know?

In notes taken during a voyage to South America on the HMS Beagle in the 1830s, Charles Darwin described an illness that he believed was caused by "miasma" emanating from stagnant pools of water. For him, miasma had the same meaning that it did when it first appeared in English in the 1600s: an emanation of a vaporous disease-causing substance. (Miasma comes from Greek miainein, meaning "to pollute.") But while Darwin was at sea, broader applications of miasma were starting to spread. Nowadays, we know germs are the source of infection, so we're more likely to use the newer, more figurative sense of miasma, which refers to something destructive or demoralizing that surrounds or permeates.

Examples of miasma in a Sentence

Recent Examples on the Web

America at 250 seems stuck in a miasma of rival populisms that offer irreconcilable visions for curing what ails our country. — Will Marshall, Washington Post, 18 July 2026

When Claudia’s ghost rips into Louis and Lestat with a miasma of rage and despair, Anderson and Reid’s eyes search for each other across the room, reflecting the unexpected agony of this experience and the regret of putting Claudia through this. — Roxana Hadadi, Vulture, 15 July 2026

The miasma of truth and fiction can become dense. — Frank Landymore, Futurism, 25 June 2026

Up in the attic, a melty miasma smothers the thick winter coats, which hurt me to even look at. — Kieran Press-Reynolds, Pitchfork, 15 June 2026

Word History

Etymology

New Latin, from Greek, defilement, from miainein to pollute

First Known Use

1665, in the meaning defined at sense 1

Rhymes for miasma

• asthma
• chiasma
• plasma
• histoplasma
• mycoplasma
• toxoplasma

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Kids Definition

miasma

noun

mi·​as·​ma mī-ˈaz-mə 

mē-

plural miasmas or miasmata -mət-ə 

1

: a vapor from a swamp formerly believed to cause disease

2

: a harmful influence or atmosphere

miasmal

-məl 

adjective

miasmatic

ˌmī-əz-ˈmat-ik 

adjective

Medical Definition

miasma

noun

mi·​as·​ma mī-ˈaz-mə  mē- 

plural miasmas also miasmata -mət-ə 

: a vaporous exhalation (as of a marshy region or of putrescent matter) formerly believed to cause disease (as malaria)

miasmal

-məl 

adjective

miasmatic

ˌmī-əz-ˈmat-ik 

adjective

miasmic

mī-ˈaz-mik  mē- 

adjective