pea soup

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A purée or soup made of cooked dried peas.
• noun Informal Dense fog.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A thick soup made with dried split peas and various other ingredients.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a heavy thick yellow fog
• noun a thick soup made of dried peas (usually made into a puree)