The term 'EYE-OPENING CUPFUL' is a combination of two crossword solutions: COFFEE (6 letters). COFFEE is a popular beverage made from roasted and ground COFFEE beans. It is usually served hot, but can also be served cold. COFFEE has been around for centuries and is enjoyed by people all over the world. The phrase 'eye-opening cupful' refers to the energizing effects of COFFEE, which can help to wake someone up and make them more alert.