'miasma' originates from Greek, specifically the word 'μῖασμα (miasma)', where 'miainein' (or 'miaein') meant 'to pollute' or 'to stain'.

'miasma' passed into Late Latin as 'miasma' and was borrowed into English (via scholarly and medical Latin usage), largely retaining its original form.

Initially, it meant 'stain' or 'pollution' in a physical or ritual sense, and in later medical usage came to mean 'poisonous or noxious vapor' thought to cause disease; today it generally means an 'unpleasant or harmful atmosphere' (literal or figurative).