Mug - a little word with so many and varied meanings.
I know it as (1) something I can drink my tea out of, (2) a fool, (3) someone's face, (4) to make silly faces, (5) to rob someone in a public place.
But the Oxford English Dictionary informs me of this meaning:
[â€˜ A mist, a fog; light rain or drizzle; a dull, damp, or gloomy atmosphere.â€™] I'd never heard that, but it's obviously related to muggy describing a hot really humid day.
How many of these did other people know?