Thick fog is a type of weather phenomenon that is characterized by a dense layer of fog that reduces visibility. The term 'thick fog' can be broken down into three crossword solutions: SOUP (4 letters), PEASOUP (7 letters), and PEASOUPER (9 letters). SOUP is a liquid food made by boiling or simmering meat, vegetables, and other ingredients in stock or water. PEASOUP is a type of SOUP made from dried peas, stock, and seasonings. PEASOUPER is an especially thick and dense fog, which is so thick that it reduces visibility to near zero.