n. pl. par·en·the·ses (-sēz′)
1. Either or both of the upright curved lines, ( ), used to mark off explanatory or qualifying remarks in writing or printing or enclose a sum, product, or other expression considered or treated as a collective entity in a mathematical operation.
a. A qualifying or amplifying word, phrase, or sentence inserted within written matter in such a way as to be independent of the surrounding grammatical structure.
b. A comment departing from the theme of discourse; a digression.
3. An interruption of continuity; an interval: "This is one of the things I wasn't prepared for—the amount of unfilled time, the long parentheses of nothing" (Margaret Atwood).
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.