The term 'SLATHERED WITH BUTTERCREAM' can be summarized by the crossword solution 'ICED, ' which is a four-letter word. Icing is a type of sweet, creamy topping that is often used to decorate cakes and other desserts. It is usually made with butter, sugar, and milk or cream, and can be flavored with extracts or spices. Slathering a cake with buttercream is a popular way to add flavor and texture to a dessert.