pea souper

/ˈpiːˌsuːpər/
noun
  1. A very thick, dense fog, often yellowish or gray, especially in cities or industrial areas.
    • Driving in a pea-souper is extremely dangerous because visibility drops to near zero.
    • The old London pea-souper was so thick you could barely see your hand in front of your face.
    • The city used to have terrible pea-soupers before air quality laws were passed.
Synonyms
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