What Is Parenthesis? (with Examples)

A typical parenthesis is a word, phrase, or clause inserted into a sentence as an explanation or afterthought. When a parenthesis is removed, the surrounding text is still grammatically sound.

A parenthesis is usually offset with parentheses (i.e., round brackets), commas, or dashes. These are called parenthetical punctuation marks.

Not all examples of parenthesis sit within a sentence. For example, a parenthesis can be one or more sentences inserted into a paragraph.

A parenthesis is sometimes called an interrupter as it interrupts the flow of text.

Examples of Parenthesis

Here are some examples of parenthesis (shaded):

Parenthesis Offset with Parentheses (Brackets)
  • Andrew Jacklin (last year's losing finalist) is expected to win this heat.
  • The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary. (H L Mencken, 1880-1956)
When parentheses (round brackets) are used to offset a parenthesis, the parenthesis is easily seen. However, some writers feel that parentheses can make formal texts look unorganized.

Parenthesis Offset with Commas
  • Paul, on the other hand, is considered extremely trustworthy.
  • House prices in Alton, which is only 25 minutes from London, are soaring.
  • Mathematics, rightly viewed, possesses not only truth but supreme beauty. (Bertrand Russell, 1872-1970)
When commas are used to offset a parenthesis, it keeps the focus on the surrounding text. As commas play other roles in sentences (e.g., to separate list items and to offset adverbial phrases), readers can sometimes become confused over where a parenthesis starts and ends.

Also, if a parenthesis itself contains a comma or commas, it is advisable to avoid commas to offset it. For example:
  • Dave Bellamy, like his father, Peter Bellamy, last year, was victorious in this year's regional pie-making finals.
  • (This could be confusing.)

  • Dave Bellamy (like his father, Peter Bellamy, last year) was victorious in this year's regional pie-making finals.
  • (This version is clearer.)
Parenthesis Offset with Dashes
  • They roasted the winning brisket — the size of pillow — in a mighty clay oven.
  • If mankind minus one were of one opinion, then mankind is no more justified in silencing the one than the one — if he had the power — would be justified in silencing mankind. (John Stuart Mill, 1806-1873)
When dashes are used to offset a parenthesis, it increases the focus on the parenthesis.



A parenthesis is offset with two parentheses, two commas, or two dashes. If a parenthesis ends a sentence, the second one in the pair is dropped. This is the only time parenthetical punctuation marks do not appear in pairs. It is a common mistake (especially with commas) to use just one.
  • Lee, however has never caught a decent bass.
  • (Another comma is required after however.)
  • Otters a menace for fish farmers will travel miles in search of a well-stocked lake.
  • (Another dash is required after farmers.)
hot grammar tip

Hot Tip


If a parenthesis is short and obvious, it is acceptable to use no parenthetical punctuation. For example:
  • John, however, drinks like a fish.
  • John however drinks like a fish.
  • John, on the other hand, drinks like a fish.
  • John on the other hand drinks like a fish.
  • (We've not marked this wrong, but it is starting to push the bounds of acceptability. If in doubt, use parenthetical punctuation.)

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