The term 'RUM MIXER' can be broken down into two crossword solutions: COKE (4 letters) and COLA (4 letters). Both of these terms refer to a type of carbonated soft drink. COKE is a brand name owned by The Coca-Cola Company, while cola is a generic term for a variety of soft drinks that contain carbonated water, sugar, and flavorings derived from kola nuts, cinnamon, citrus, and other ingredients. Rum mixers are cocktails made with rum and either COKE or cola.