What’s the Plural of Parenthesis?

In writing, parentheses are commonly used to add extra information, clarify a point, or provide examples. They help to enclose words, phrases, or even entire sentences within a text without disrupting the main flow of information. However, many people get confused when it comes to the plural form of parenthesis. Is it parenthesises? Or perhaps something else?

In this article, we’ll explore the correct plural form of parenthesis, explain why it behaves the way it does, and provide examples of its correct usage. We’ll also answer common questions about parentheses and offer practice questions to help solidify your understanding.

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What Is the Plural of “Parenthesis”?

The plural of parenthesis is parentheses. In this case, the word parenthesis refers to one of the curved punctuation marks: ( ). When you are referring to both marks (the opening and closing symbols), or when you’re talking about more than one set of these punctuation marks, the correct plural form is parentheses.

Why Is the Plural “Parentheses”?

The word parenthesis comes from the Greek word parenthesis, which means “insertion” or “putting in beside.” In Greek, pluralization often involves more than just adding an -s; it often involves changing the ending of the word, depending on the word’s roots. English has preserved this rule, so parenthesis (singular) becomes parentheses (plural).

This pluralization pattern is similar to other English words that have Greek origins. For example:

• Thesis → Theses
• Crisis → Crises
• Analysis → Analyses

In each of these examples, the singular form ends in -is, and the plural form ends in -es. The same rule applies to parenthesis, making its plural parentheses.

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Is “Parenthesises” Ever Correct?

No, parenthesises is not correct. The correct plural form for parenthesis is always parentheses. While some English speakers may mistakenly add an -es or -s to form the plural, this is grammatically incorrect because, as mentioned earlier, parenthesis follows the Greek rule of pluralization.

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What Is a Parenthesis?

Before we dive deeper into examples and usage, let’s clarify what parenthesis means:

A parenthesis (singular) refers to one of the two curved marks ( ) used in writing to insert additional information into a sentence. These marks are used to separate non-essential or explanatory content from the main sentence. For example:

• John (my brother) is coming to visit this weekend.

In this sentence, the parentheses enclose the additional information my brother, which explains who John is without altering the core meaning of the sentence.

Parentheses (plural):

When we use parentheses (plural), we are referring to the pair of symbols ( ). These marks are always used in pairs—the opening mark ( and the closing mark )—to set off the enclosed content.

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Examples of “Parenthesis” and “Parentheses” in Sentences

Let’s look at some examples to clarify the correct usage of parenthesis and parentheses in both singular and plural contexts.

Singular Form of “Parenthesis”:

• The author included a single parenthesis to add a note at the end of the sentence.
  (Here, parenthesis refers to one of the punctuation marks.)
• You used the wrong parenthesis when quoting the source.
  (In this sentence, parenthesis refers to one of the two curved marks.)
• Make sure you close the parenthesis after inserting the author’s name.
  (This example uses parenthesis to refer to one closing symbol.)

Plural Form “Parentheses”:

• The editor noticed that several parentheses were left open in the manuscript.
  (Here, parentheses refers to multiple pairs of these punctuation marks.)
• The math equation was enclosed in parentheses to clarify the order of operations.
  (In this sentence, parentheses refers to the pair of punctuation marks that enclose the equation.)
• Be sure to include the page number in parentheses when citing your sources.
  (This example shows parentheses being used to enclose additional information.)

Using “Parenthesis” and “Parentheses” in Different Tenses:

• Present Tense:
• He is using a parenthesis to clarify the point.
  (Singular: parenthesis refers to one of the curved marks.)
• They are adding extra notes in parentheses for clarity.
  (Plural: parentheses refers to multiple pairs of marks.)
• Past Tense:
• She used a parenthesis to include the birth year of the author.
  (Singular: parenthesis refers to one punctuation mark.)
• The writer added several examples in parentheses throughout the essay.
  (Plural: parentheses refers to multiple instances of the punctuation marks.)

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Common Questions About “Parentheses” and Their Usage

Let’s address some frequently asked questions to clarify any confusion about the pluralization and usage of parenthesis and parentheses.

Question 1:

Is “parentheses” always plural?

Answer:
Yes, parentheses is always plural. It refers to the pair of punctuation marks ( ) that are used together. If you’re talking about a single one of these marks (either the opening or closing mark), the correct term is parenthesis (singular). When referring to both marks or multiple sets of marks, use parentheses.

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Question 2:

Can you say “a pair of parentheses”?

Answer:
Yes, you can say “a pair of parentheses” to emphasize that you are referring to both the opening mark ( and the closing mark ). This phrase is often used to clarify that parentheses come in pairs.

Example:

• Make sure to include a pair of parentheses around the citation.

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Question 3:

Is “parenthesises” ever correct?

Answer:
No, parenthesises is not correct. The proper plural form of parenthesis is parentheses, following the Greek pluralization rule. Parenthesises is a common mistake but is not grammatically acceptable.

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Question 4:

What is the purpose of parentheses in writing?

Answer:
Parentheses are used in writing to set off or enclose non-essential information, clarifications, examples, or afterthoughts that are not necessary for the main meaning of the sentence but provide additional context or details.

For example:

• The dessert (which was delicious) was made by my grandmother.

In this sentence, the phrase which was delicious is not essential to the core meaning but adds extra information about the dessert.

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Question 5:

Are there other punctuation marks that behave like parentheses?

Answer:
Yes, there are other punctuation marks that serve similar purposes, though they are used for slightly different reasons. These include:

• Brackets: Used primarily to enclose additional information, corrections, or clarifications within quotations.
  Example: He said, “It [the event] was a success.”
• Braces: Typically used in mathematical or technical contexts to group sets of items or numbers.
  Example: {1, 2, 3}
• Dashes: Used to insert additional information or an interruption into a sentence.
  Example: The meeting—although brief—was very productive.

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Practice Questions: Using “Parenthesis” and “Parentheses” Correctly

Let’s test your understanding of how to use parenthesis and parentheses with the following practice questions.

Question 1:

Fill in the blank with the correct plural form:

The writer added several clarifications in _ throughout the document.

a) parenthesis
b) parentheses
c) parenthesises

Answer:
b) parentheses

Explanation: The correct plural form is parentheses. Parenthesis is singular, and parenthesises is incorrect.

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Question 2:

Which sentence is grammatically correct?

a) The author used a single parentheses to enclose the date of publication.
b) The author used a single parenthesis to enclose the date of publication.
c) The author used a single parenthesises to enclose the date of publication.

Answer:
*b) The author used a single parenthesis to enclose the date of publication.

Explanation: Parenthesis is singular and correctly used here to refer to one of the punctuation marks. Parentheses is the plural form, and parenthesises is incorrect.

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Question 3:

True or False:
“Parentheses” can refer to just one of the curved punctuation marks.

Answer:
False

Explanation: Parentheses is always plural and refers to both the opening and closing marks as a pair. The singular form is parenthesis, which refers to just one of the marks.

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Question 4:

What is the singular form of “parentheses”?

a) parenthesis
b) parenthesises
c) parenthesi

Answer:
a) parenthesis

Explanation: Parenthesis is the singular form, referring to one of the two punctuation marks in a pair.

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Singular and Plural Forms of Other “Greek-Origin” Words Ending in “-is”

To further clarify how parenthesis fits into the broader category of Greek-origin words, let’s look at a few more examples. These words follow the same pattern, where the singular ends in -is and the plural ends in -es.

Words That Follow the “-is” to “-es” Rule:

• Parenthesis → Parentheses
• The extra information was added in a single parenthesis.
• Several explanations were enclosed in parentheses.
• Thesis → Theses
• Her thesis on climate change was well researched.
• The university published several prize-winning theses.
• Crisis → Crises
• The government responded to the economic crisis quickly.
• Multiple crises have affected the region in recent years.
• Hypothesis → Hypotheses
• The scientist proposed a new hypothesis about the origin of the universe.
• The researchers tested several hypotheses to explain the phenomenon.

These words retain their original Greek pluralization rules, making them exceptions to the usual English pattern of pluralizing nouns by adding -s or -es.

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Conclusion

The plural of parenthesis is parentheses, following the Greek rule for pluralizing words that end in -is. While it might be tempting to add -es or -s in line with regular English pluralization rules, this is incorrect. Parentheses is the proper plural form and should be used in all writing contexts.

Key Takeaways:

• The correct plural form of parenthesis is parentheses.
• Parenthesises is incorrect and should not be used.
• Parentheses is always plural and refers to both the opening and closing marks ( ).
• Parenthesis is the singular form, referring to just one of the curved punctuation marks.

By understanding the proper pluralization of parenthesis, you can confidently use the word in both written and spoken English, ensuring clarity and accuracy in your communication!