Upper limits refer to the highest possible value or amount of something. The term can be broken down into four crossword solutions: MAXIMUMS (8 letters), CAPS (4 letters), CEILINGS (8 letters), and MAXIMA (6 letters). MAXIMUMS and MAXIMA both refer to the highest possible amount of something, while CAPS and CEILINGS refer to the highest possible value of something. All four terms are used to describe the same concept, which is the highest possible limit of something.