The term 'SOAP STUFF' can be broken down into two crossword solutions: OLEATE (6 letters) and LYE (3 letters). OLEATE is a type of fatty acid derived from oils and fats, and is commonly used in the production of soap. LYE is a type of alkaline solution, usually made from sodium hydroxide or potassium hydroxide, which is also used in the production of soap. Together, these two ingredients are essential components of soap-making.