fog up

1. 1.

   get foggy

   “The windshield fogged up”

   Broaderovercast

Questions about fog up

What does fog up mean?

fog up means "get foggy".

Is fog up a common word?

fog up is banded "Uncommon" — turns up in careful writing rather than conversation. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.