Non-defining clauses add additional information about a noun or a pronoun in a sentence. This extra information is not essential to understand the main point; it's just there to add more detail. Non-defining clauses are always set off by commas.
Using Non-defining Clauses
Non-defining clauses usually begin with who, whom, whose, which, or where. They cannot begin with that.
Examples
- My sister, who lives in New York, is visiting us next week.
- The book, which has a blue cover, is on the table.
- Mr. Smith, who is our teacher, will help us with the project.
Key Points
- Non-defining clauses add extra information.
- They are always separated by commas.
- They cannot use that as a relative pronoun.
- If the relative pronoun refers to a person, who, whom, or whose is used.
- If it refers to a thing, which is used.
- If it refers to a place, where can be used.
Relative Pronouns in Non-defining Clauses
| Pronoun | Refers To | Example |
|---|---|---|
| who | people (subject) | My uncle, who is a doctor, is very kind. |
| whom | people (object) | Mrs. Jones, whom I met yesterday, is very tall. |
| whose | people or things (possession) | The author, whose book won an award, is here. |
| which | things | The car, which is red, is fast. |
| where | places | Paris, where I studied, is beautiful. |
Can Non-defining Clauses Be Reduced?
Yes, sometimes you can reduce non-defining clauses, especially if the relative pronoun is who and the verb is be. You do this by removing the relative pronoun and the verb be.
Examples
| Full Clause | Reduced Clause |
|---|---|
| My brother, who is a lawyer, works in London. | My brother, a lawyer, works in London. |
| The woman, who was standing there, is my aunt. | The woman, standing there, is my aunt. |
Common Mistakes
| Mistake | Explanation | Correct Form |
|---|---|---|
| Using that | That cannot be used in non-defining clauses. | The cake, which was delicious, was homemade. |
| Omitting commas | Commas are necessary to set off the clause. | My father who is retired watches TV all day. |
| Incorrect pronoun | Using the wrong relative pronoun causes errors. | The movie, who won awards, is great. |
Summary
Non-defining clauses add extra, non-essential information to nouns. They are always set off by commas and cannot use that as a relative pronoun. They help make your writing more detailed and interesting.
Last updated: Wed Jun 18, 2025
