— insertion of some verbal unit in a position that interrupts the normal syntactical flow of the sentence, thereby sending the thought off on an important tangent that has pronounced rhetorical effect. Often involves literal parentheses ( ), but not always; there are other ways to insert a comment into a sentence. One might use commas, or dashes, for example. The parenthetical remark, however, is off on a tangent, cut off from the thrust of the sentence and grammatically unrelated to the sentence.
"Those two spots are among the darkest of our whole civilization—pardon me, our whole culture (an important distinction, I've heard), which might sound like a hoax, or a contradiction, but that (by contradiction, I mean) is how the world moves: not like an arrow, but a boomerang." (Ralph Ellison, Invisible Man)
"And they went further and further from her, being attached to her by a thin thread (since they had lunched with her) which would stretch and stretch, get thinner and thinner as they walked across London; as if one's friends were attached to one's body, after lunching with them, by a thin thread, which (as she dozed there) became hazy with the sound of bells, striking the hour or ringing to service, as a single spider's thread is blotted with rain-drops, and burdened, sags down. So she slept."—Virginia Woolf, Mrs. Dalloway
"He said he supervised ten editors--another euphemism--in his department, which clears 90% of NBC's entertainment programming..." (Joan Barthel, in Life magazine, August 1969)
"There is even, and it is the achievement of this book, a curious sense of happiness running through its paragraphs." (Norman Mailer, book review)
