This is the 773rd most frequent Swedish word.
os
"Os" in Swedish means "smoke" or "fume" in English.
Here, "os" is used to denote smoke or fume in the context of something being emitted from a source.
Det är mycket os som kommer från elden.
There is a lot of smoke coming from the fire.
In this sentence, "os" refers to an unpleasant smell, often related to smoke or similar airborne particles.
Han ogillade osen av cigarrer.
He disliked the smell of cigars.
This shows "os" being used to describe the emission that comes from a kitchen accident, again relating to unpleasant airborne substances.