Parenthetical Expressions

A parenthetical expression is a phrase or clause that’s inserted within—in effect, it interrupts—another phrase or clause. The larger structure is complete without the smaller structure, which could be an adverb clause, as in the following four examples, or an added comment or remark that has no syntactic function in the clause. I’ve italicized the parenthetical expressions, including the one in the first sentence in this paragraph. Note that the expressions are enclosed in (surrounded by) pairs of punctuation marks: commas or parentheses (round brackets), or dashes:

Strawberry jam, for instance, doesn’t make a good spaghetti sauce.

Uncle Charlie, when he was told about the escaped fleas, broke out in a blush.

Cobras, although they are essentially moody, like an occasional chuckle.

The tone of her letter, however, brought tears to Fang’s eyes.

It’s important to note that the commas that surround phrases and clauses that are inserted between backbone functions don’t violate the rule that no punctuation can separate subjects and finite verbs: the punctuation “belongs” to the parenthetical expression:

Fang, in fact, was furious.

But, of course, Miss Hiss was amused.

Jumbo, it seems, prefers peanuts in soy sauce.

Parentheses (or round brackets) set off material that is inserted as an explanation or comment. The idea is to add information rather quietly (a brief definition or comment, for example), so as not to distract the reader from the rest of the sentence:

Uncle Charlie (a reformed gargler) met Aunt Min (at that time a mouthwash therapist) at a poltergeists’ convention.

Charlie was looking for a dealership in rubber adverbs (used in very tight clauses), but he would have willingly fallen back on wooden appositives (a boon for the unimaginative essayist).

When I can’t think of any appropriate silly examples (for instance, after a strenuous evening with the Boa Brothers), I try standing on my head.

In the sentence about Uncle Charlie and Aunt Min, no punctuation follows either parenthesis because none would have been used without the parentheses. In the second and third sentences, the commas that would ordinarily follow adverbs and examples come after the closing parenthesis marks. The rule is that the expression in parentheses should come immediately after the structure it comments on, before any other punctuation.

A pair of dashes is used to emphasize parenthetical expressions more forcefully:

Monty the Python—a snake in the grass if I ever saw one—often pretends to have fang aches.

Orange-nosed attack frogs—there’s one on your shoulder now—defeat their enemies by sucking out their wits.

If I’m allowed to write a serious example sentence for once—I’ll probably be lynched for it—I’d say that it’s best to use dashes sparingly.

Jack was injured by a booby-trapped plum—or so he claims.

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20 comments on “Parenthetical Expressions
  1. Arlene MacGregor says:

    I find this article to be, although serious in terms of grammar, very funny.

  2. Joe Bob says:

    Thanks lots of help!!!!!!!!!!!!

  3. mj says:

    Your humor was great! My students didn’t get it at first, but once they did, they loved it. Which made them eager to continue with the lesson and the examples. You tricked them into becoming engaged in the learning process! 🙂 Thank you.

  4. Would you use commas to set off what would otherwise constitute a parenthetical expression when it tends to be a “continuation” as oppose to an “interruption.” Example:

    Continuation: We therefore need to leave early.

    Interruption: We need, therefore, to leave early.

    • Dr_Ron_Rower says:

      Hi, James,

      I apologize for such a long delay in responding to your query: the site was hacked and was only recently put to rights.

      You’ve punctuated correctly of course. I see I never covered this situation (in Restrictive and Non-restrictive Modifiers) and the options are rather fuzzy in my mind. It seems to be a matter of rhythm: if this kind of adverb comes directly before the verb it modifies, there’s no punctuation, as you say, the rhythm is continuous. Anywhere else in the sentence there’s a pause. In both cases the adverb refers in meaning to a previous sentence, such as It will snow tomorrow.

      Ron 🙂

  5. Tiffany says:


  6. Jan says:

    Thank you so much for this absorbing and witty lesson. I am sure I will visit your page often.
    I was always confused about the use of parentheses and you have cleared that up for me.

  7. Jane says:

    What if you say:

    Jack — and his friend Jill — goes up the hill.

    Fear — and the anxiety it arouses — is driving a lot of Trump’s support.

    Should these be singular or plural — “goes” or “go,” “are” or “is”? And why?

    Thank you!

  8. Kizza Gorret says:

    Thanks for the lesson on parentheticals, I didn’nt know how they were called in sentences.

  9. Maria says:

    There’s one sentence by Aldous Huxley that says,”In no city, West or East, have I ever had such an impression of dense, rank, richly clotted life.” How to understand “west or east” here, are they adjectives or adverbs or what? Thanks.

  10. mohamed ahmed says:

    thanks for the explaining but Im confusing i want simply examples about the different between parenthetical and nonparathetical

    • Dr_Ron_Rower says:

      Hi, Mohammed, I must suggest you reread the examples in the section on parenthetical expressions. The non-parenthetical is the main thing you want to say, the parenthetical is what you might say in addition to the main thing, but is not necessary and could be left out altogether. Regards, Dr Ron

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