The crossword solution for the term MAYO INGREDIENT is 'EGG' (3 letters). Eggs are a common ingredient in mayonnaise, which is an emulsion of oil, EGG yolks, and either vinegar or lemon juice. The EGG yolks provide the creamy texture and flavor to the mayonnaise. Eggs also act as an emulsifier, helping to bind the oil and vinegar together. Additionally, eggs provide a source of protein and other nutrients.