parentheses

Parentheses ( ( ) ) are used to separate information that is not necessary to the structure or meaning of the surrounding text.

pa·ren·the·sis

(pə-rĕn′thĭ-sĭs)

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).

[Late Latin, insertion of a letter or syllable in a word, from Greek, from parentithenai, to insert : para-, beside; see para-¹ + en-, in; see en in Indo-European roots + tithenai, to put; see dhē- in Indo-European roots.]

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

square brackets, parentheses, braces - Square brackets were formerly called crotchets, round brackets are commonly called parentheses, and curly brackets are called braces; the punctuation called brackets derives from the bookshelf type, implying that, in writing, these marks "lift up" a section of a sentence.