The term MILK BUY can be broken down into four crossword solutions: PINT (4 letters), CARTON (6 letters), GALLON (6 letters), and QUART (5 letters). Pint is a unit of measurement for liquid volume, equal to one-eighth of a gallon. A CARTON is a type of packaging typically used for milk, juice, and other beverages. A gallon is a unit of measurement for liquid volume, equal to four quarts. Finally, a quart is a unit of measurement for liquid volume, equal to one-fourth of a gallon.