Doubly even is a mathematical term used to describe a number that is divisible by two and also divisible by four. However, there are several synonyms for the term, such as quadruple even, even-squared, and even-even. These synonyms are used in different areas of mathematics, such as algebra and number theory. In algebra, quadruple even is used to describe a number that is divisible by four, while in number theory, even-squared denotes a number that is the product of an even number and itself. Overall, all these synonyms signify a numeric pattern that is divisible by an even number.