A clear soup is any soup made without thickeners or dairy products, according to About.com. Unlike a thick soup, clear soup is typically fairly transparent.
Clear soups are made by simmering meat, poultry, fish or vegetables in liquid to create a broth. The broth can be served on its own, or it can be used as the basis for an augmented clear soup. Well-known clear soups include chicken noodle soup, matzo ball soup, Vietnamese pho noodle soup and Italian brodo. With all of these soups, even though the bowl may be filled with many ingredients, the broth itself is transparent and contains no dairy or other thickeners.