The term REUBEN INGREDIENT is composed of five crossword solutions: SAUERKRAUT (10 letters), SWISS (5 letters), KRAUT (5 letters), RYEBREAD (8 letters), and SWISSCHEESE (11 letters). SAUERKRAUT is a type of fermented cabbage, usually made with white cabbage and salt. SWISS is a type of cheese, usually made from cow's milk and characterized by its holes. Kraut is another name for SAUERKRAUT. Rye bread is a type of bread made with rye flour, which is a type of grain. SWISS cheese is a type of cheese similar to Emmental cheese, but with a milder flavor. All of these ingredients are commonly used in the classic Reuben sandwich.