A noxious atmosphere or influence; a thick vaporous atmosphere or emanation.
Dated back to the 1660’s, the Latin word miasma stood for noxious vapors stemming from the same Greek noun representing a stain, pollution, defilement or a taint of guilt. In the late 14th century, prior to this meaning, the Proto Indo European root of mai also gave birth to the English word mole, specifically referring dark marks or stains on human skin.
Why this word?
Whether in a smoky bar, or with a meeting at work, we often find ourselves feeling simply sick, physically or mentally, due to the situation we are in. You can say that the atmosphere at the office is lately unpleasant, but if you use this word you would give this atmosphere the repelling scent of ancient toxic swaps, places leading to your slow and painful death if you stick around for too long… Sometimes this word is exactly what you need.
How to use miasma?
For actual and physical miasma you can say “the bar was filled with a miasma of sweat, old liquor and stake cigarette smoke… I wanted to leave as soon as I walked in“. If you are referring to a mental situation, the adjective would surely work better than the noun. “I love Dana so much, but her family’s influence over her is completely miasmal; she now wants me to quit my job!“
You can also address one’s miasmic attempts to do something negative or their miasmic and hurtful words.