The crossword solution for the term 'Complete Groups' is SETS, which is a four-letter word. SETS refers to a group of objects or individuals that are related in some way and have something in common. A set can be composed of any number of elements, and the elements can be of any type. Sets are often used in mathematics, where they are used to describe relationships between numbers or other mathematical objects. In everyday life, sets are used to group people, objects, or ideas together.