parentheses

This term refers specifically to the pair of marks. While it is the plural form of parenthesis, it is most commonly used in English to describe the set of symbols as a single functional unit. In technical or mathematical contexts, it denotes the boundary markers that dictate the order of operations.

Because the word is inherently plural in its common usage to describe the pair ( ), it is often treated as a plural noun. When referring to a single mark, the singular form parenthesis is used, though in casual speech, people frequently refer to a single mark as a parenthesis or simply a bracket.