Defining and Non-Defining Relative Clauses: A Comprehensive Guide

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Relative clauses are essential for adding detail and complexity to your sentences. They allow you to provide extra information about nouns, making your writing more descriptive and engaging.

Understanding the difference between defining and non-defining relative clauses is crucial for using them correctly. This article will provide a comprehensive guide to defining and non-defining relative clauses, including definitions, examples, usage rules, common mistakes, and practice exercises.

Whether you’re a beginner or an advanced learner, this guide will help you master this important aspect of English grammar.

Table of Contents

Definition of Relative Clauses

A relative clause is a type of subordinate clause that modifies a noun or noun phrase. It provides additional information about the noun it modifies, helping to identify or describe it further. Relative clauses are introduced by relative pronouns (who, whom, which, that, whose) or relative adverbs (where, when, why).

Defining Relative Clauses

A defining relative clause, also known as a restrictive relative clause, is essential to the meaning of the sentence. It identifies the noun it modifies, specifying which particular noun is being referred to.

Without the defining relative clause, the sentence would be unclear or incomplete. Defining relative clauses are not set off by commas.

Non-Defining Relative Clauses

A non-defining relative clause, also known as a non-restrictive relative clause, provides extra information about a noun that is already clearly identified. This information is not essential to the meaning of the sentence; it simply adds detail.

Non-defining relative clauses are always set off by commas.

Structural Breakdown

Understanding the structure of relative clauses is key to using them correctly. This involves knowing which relative pronouns and adverbs to use and how to place the clause within the sentence.

Relative Pronouns and Adverbs

Relative pronouns and adverbs connect the relative clause to the main clause. The choice of pronoun or adverb depends on the noun being modified and the role it plays in the relative clause.

  • Who: Used for people when the relative pronoun is the subject of the clause. Example: The woman who lives next door is a doctor.
  • Whom: Used for people when the relative pronoun is the object of the verb or preposition in the clause. Example: The man whom I saw yesterday is my teacher. (Often replaced by “who” in informal speech.)
  • Which: Used for things or animals. Example: The car which I bought last year is very reliable.
  • That: Used for people, things, or animals in defining relative clauses. Example: The book that I’m reading is fascinating.
  • Whose: Used to show possession for people, things, or animals. Example: The student whose essay won the prize is very talented.
  • Where: Used to refer to a place. Example: The city where I grew up is very different now.
  • When: Used to refer to a time. Example: The day when I graduated was very special.
  • Why: Used to refer to a reason. Example: The reason why I’m late is because of the traffic.

Clause Placement

The placement of the relative clause depends on whether it is defining or non-defining. Defining relative clauses are placed immediately after the noun they modify.

Non-defining relative clauses are also placed immediately after the noun they modify, but they are set off by commas.

Types of Relative Clauses

The two main types of relative clauses are defining and non-defining, as previously discussed. The key difference lies in their essentiality to the sentence’s meaning and their punctuation.

Examples of Defining and Non-Defining Relative Clauses

The best way to understand the difference between defining and non-defining relative clauses is to look at examples.

Defining Relative Clause Examples

These examples illustrate how defining relative clauses provide essential information that identifies the noun being referred to. Removing the clause would leave the sentence unclear.

The following table provides examples of defining relative clauses:

Sentence with Defining Relative Clause Explanation
The book that I borrowed from the library is due tomorrow. The clause identifies which specific book is being referred to.
The student who studies hard usually gets good grades. The clause identifies which student is being referred to.
The car that was parked illegally was towed away. The clause identifies which car is being referred to.
People who are kind are often well-liked. The clause identifies which people are being referred to.
The restaurant where we had dinner last night was excellent. The clause identifies which restaurant is being referred to.
The movie that won the award was very moving. The clause identifies which movie is being referred to.
The teacher who taught me English was very patient. The clause identifies which teacher is being referred to.
The house that is on the corner is for sale. The clause identifies which house is being referred to.
The dog that barks loudly lives next door. The clause identifies which dog is being referred to.
The song that I heard on the radio is stuck in my head. The clause identifies which song is being referred to.
The shoes that I bought yesterday are very comfortable. The clause identifies which shoes are being referred to.
The phone that I lost was brand new. The clause identifies which phone is being referred to.
The man who is wearing a hat is my father. The clause identifies which man is being referred to.
The woman who is talking on the phone is my sister. The clause identifies which woman is being referred to.
The child who is playing in the park is my son. The clause identifies which child is being referred to.
The tree that is in the garden is very old. The clause identifies which tree is being referred to.
The computer that I use for work is very slow. The clause identifies which computer is being referred to.
The city where I was born is very small. The clause identifies which city is being referred to.
The reason why I am here is complicated. The clause identifies which reason is being referred to.
The time when I met her was unforgettable. The clause identifies which time is being referred to.
The cake that she baked was delicious. The clause identifies which cake is being referred to.
The flowers that are in the vase are beautiful. The clause identifies which flowers are being referred to.
The painting that hangs in the museum is famous. The clause identifies which painting is being referred to.
The project that we are working on is very important. The clause identifies which project is being referred to.
The game that they are playing is very exciting. The clause identifies which game is being referred to.
The animal that lives in the forest is a deer. The clause identifies which animal is being referred to.
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Non-Defining Relative Clause Examples

These examples illustrate how non-defining relative clauses provide extra information that is not essential to the meaning of the sentence. Removing the clause would not make the sentence unclear, but it would remove some detail.

Note the comma usage.

The following table provides examples of non-defining relative clauses:

Sentence with Non-Defining Relative Clause Explanation
My sister, who lives in London, is a doctor. The clause provides extra information about “my sister,” who is already identified.
The Eiffel Tower, which is a famous landmark, is located in Paris. The clause provides extra information about “The Eiffel Tower,” which is already identified.
My car, which is very old, still runs well. The clause provides extra information about “my car,” which is already identified.
Shakespeare, who wrote many famous plays, is considered one of the greatest writers in the English language. The clause provides extra information about “Shakespeare,” who is already identified.
Paris, where I spent my honeymoon, is a beautiful city. The clause provides extra information about “Paris,” which is already identified.
My birthday, which is next week, will be a small celebration. The clause provides extra information about “my birthday,” which is already identified.
My dog, who loves to play fetch, is very energetic. The clause provides extra information about “my dog,” who is already identified.
My house, which is located near the park, is very convenient. The clause provides extra information about “my house,” which is already identified.
The Amazon River, which is the second longest river in the world, is located in South America. The clause provides extra information about “The Amazon River,” which is already identified.
My best friend, who I have known since childhood, is getting married. The clause provides extra information about “my best friend,” who is already identified.
My phone, which I bought last month, is already broken. The clause provides extra information about “my phone,” which is already identified.
My favorite restaurant, which is downtown, is very expensive. The clause provides extra information about “my favorite restaurant,” which is already identified.
My neighbor, who is a retired teacher, is very knowledgeable. The clause provides extra information about “my neighbor,” who is already identified.
My parents, who live in the countryside, visit me often. The clause provides extra information about “my parents,” who are already identified.
My grandmother, who is 90 years old, is still very active. The clause provides extra information about “my grandmother,” who is already identified.
My cat, who loves to sleep all day, is very lazy. The clause provides extra information about “my cat,” who is already identified.
My office, which is on the third floor, has a great view. The clause provides extra information about “my office,” which is already identified.
Rome, which I visited last year, is a historical city. The clause provides extra information about “Rome,” which is already identified.
Christmas, which is celebrated on December 25th, is a popular holiday. The clause provides extra information about “Christmas,” which is already identified.
My watch, which I received as a gift, is very valuable. The clause provides extra information about “my watch,” which is already identified.
My garden, which is full of flowers, is very colorful. The clause provides extra information about “my garden,” which is already identified.
My school, which is located in the city center, is very modern. The clause provides extra information about “my school,” which is already identified.
My job, which is very demanding, is also very rewarding. The clause provides extra information about “my job,” which is already identified.
My book, which I have been writing for years, is finally finished. The clause provides extra information about “my book,” which is already identified.
My project, which I presented yesterday, was well-received. The clause provides extra information about “My project,” which is already identified.
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Usage Rules

There are specific rules for using defining and non-defining relative clauses correctly. These rules involve punctuation, pronoun choice, and the use of “that” vs.

“which.”

Punctuation Rules

The most important punctuation rule is that non-defining relative clauses are always set off by commas, while defining relative clauses are not. This is the key visual distinction between the two types of clauses.

Consider these examples:

  • Defining: The house that I bought is very old. (No commas because the clause identifies which house.)
  • Non-Defining: My house, which I bought last year, is very old. (Commas because the clause provides extra information about a specific house.)

Pronoun Choice

The choice of relative pronoun depends on the noun being modified and its role in the relative clause. As a general rule:

  • Use who or whom for people.
  • Use which for things or animals (in non-defining clauses).
  • Use that for people, things, or animals (in defining clauses).
  • Use whose to show possession.
  • Use where for places.
  • Use when for times.
  • Use why for reasons.

“That” vs. “Which”

The use of “that” and “which” can be confusing. The general rule is:

  • Use that in defining relative clauses.
  • Use which in non-defining relative clauses.

However, in some informal contexts, “which” can be used in defining relative clauses, although “that” is generally preferred.

Examples:

  • Defining: The car that I want to buy is expensive.
  • Non-Defining: My car, which is very reliable, is ten years old.

Common Mistakes

Here are some common mistakes to avoid when using defining and non-defining relative clauses:

Incorrect Correct Explanation
The book, that I borrowed from the library is due tomorrow. The book that I borrowed from the library is due tomorrow. “That” is used in defining relative clauses, which do not take commas.
My sister who lives in London, is a doctor. My sister, who lives in London, is a doctor. Non-defining relative clauses are always set off by commas.
The car, which I want to buy is expensive. The car that I want to buy is expensive. This is a defining clause, so it should use “that” and no commas.
My house which is near the park is very convenient. My house, which is near the park, is very convenient. “My house” is already specific, so this requires commas and ‘which’.
People who’s kind are often well-liked. People who are kind are often well-liked. “Who’s” is a contraction of “who is,” not the possessive pronoun.

Practice Exercises

Test your understanding of defining and non-defining relative clauses with these exercises.

Exercise 1: Identifying Defining and Non-Defining Clauses

Identify whether each sentence contains a defining or non-defining relative clause.

Sentence Defining or Non-Defining
The movie that I saw last night was amazing.
My friend, who is a teacher, loves her job.
The book which is on the table is mine.
My hometown, which is very small, is peaceful.
The person who helped me was very kind.
My car, which is red, is parked outside.
The restaurant where we ate dinner was closed.
My vacation, which I took last summer, was relaxing.
The dog that is barking is very loud.
My phone, which is new, is already having problems.

Answers:

Sentence Defining or Non-Defining
The movie that I saw last night was amazing. Defining
My friend, who is a teacher, loves her job. Non-Defining
The book which is on the table is mine. Defining
My hometown, which is very small, is peaceful. Non-Defining
The person who helped me was very kind. Defining
My car, which is red, is parked outside. Non-Defining
The restaurant where we ate dinner was closed. Defining
My vacation, which I took last summer, was relaxing. Non-Defining
The dog that is barking is very loud. Defining
My phone, which is new, is already having problems. Non-Defining

Exercise 2: Adding Relative Clauses

Add a relative clause to each sentence. Indicate whether the clause is defining or non-defining and punctuate accordingly.

Sentence Your Answer Defining or Non-Defining
The man is a doctor.
My house is very old.
The book is interesting.
My friend is coming to visit.
The city is beautiful.
The movie was very long.
My teacher is very helpful.
The car is broken.
My dog is very playful.
The phone is ringing.

Example Answers: (Multiple answers possible)

Sentence Example Answer Defining or Non-Defining
The man is a doctor. The man who is wearing a blue shirt is a doctor. Defining
My house is very old. My house, which I bought last year, is very old. Non-Defining
The book is interesting. The book that I’m reading is interesting. Defining
My friend is coming to visit. My friend, who lives in Canada, is coming to visit. Non-Defining
The city is beautiful. The city where I grew up is beautiful. Defining
The movie was very long. The movie that we watched last night was very long. Defining
My teacher is very helpful. My teacher, who is from Spain, is very helpful. Non-Defining
The car is broken. The car that is parked outside is broken. Defining
My dog is very playful. My dog, who loves to chase balls, is very playful. Non-Defining
The phone is ringing. The phone that is on the table is ringing. Defining
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Exercise 3: Correcting Mistakes

Correct the mistakes in the following sentences related to relative clauses.

Incorrect Sentence Corrected Sentence
The woman, that I met yesterday, was very nice.
My car which is blue is parked outside.
The book, which I’m reading is very interesting.
My friend who lives in London is a doctor.
The house that, is on the corner is for sale.
My dog, who’s tail wags constantly, is happy.
The reason, why I’m late is because of traffic.
My birthday which is next week, is on a Tuesday.
The student whom studies hard gets good grades.
My phone that I bought last week, is already broken.

Answers:

Incorrect Sentence Corrected Sentence
The woman, that I met yesterday, was very nice. The woman that I met yesterday was very nice.
My car which is blue is parked outside. My car, which is blue, is parked outside.
The book, which I’m reading is very interesting. The book that I’m reading is very interesting.
My friend who lives in London is a doctor. My friend, who lives in London, is a doctor.
The house that, is on the corner is for sale. The house that is on the corner is for sale.
My dog, who’s tail wags constantly, is happy. My dog, whose tail wags constantly, is happy.
The reason, why I’m late is because of traffic. The reason why I’m late is because of traffic.
My birthday which is next week, is on a Tuesday. My birthday, which is next week, is on a Tuesday.
The student whom studies hard gets good grades. The student who studies hard gets good grades.
My phone that I bought last week, is already broken. My phone, which I bought last week, is already broken.

Advanced Topics

For advanced learners, there are more complex aspects of relative clauses to explore.

Reduced Relative Clauses

Reduced relative clauses are shortened forms of relative clauses, where the relative pronoun and auxiliary verb are omitted. This is possible when the relative pronoun is the subject of the clause.

Example:

  • Full: The book that is lying on the table is mine.
  • Reduced: The book lying on the table is mine.

Relative Clauses with Prepositions

Relative clauses can include prepositions, which can be placed either before the relative pronoun (in formal writing) or at the end of the clause (in informal writing).

Examples:

  • Formal: The person to whom I spoke was very helpful.
  • Informal: The person who I spoke to was very helpful.

FAQ

Here are some frequently asked questions about defining and non-defining relative clauses:

  1. What is the main difference between defining and non-defining relative clauses?

    The main difference is that defining relative clauses are essential to the meaning of the sentence, while non-defining relative clauses provide extra, non-essential information. Defining clauses are not set off by commas, while non-defining clauses are.

  2. When should I use “that” versus “which”?

    Generally, use “that” in defining relative clauses and “which” in non-defining relative clauses. However, in informal contexts, “which” can sometimes be used in defining clauses, although “that” is preferred.

  3. Can I use “who” for things?

    No, “who” is only used for people. Use “which” or “that” for things or animals.

  4. What happens if I use commas incorrectly?

    Incorrect use of commas can change the meaning of the sentence. Omitting commas from a non-defining clause or adding them to a defining clause can lead to confusion.

  5. Can I omit the relative pronoun?

    In some cases, you can omit the relative pronoun in defining relative clauses when it is the object of the verb in the clause. For example, “The book I read was interesting” is correct, but you cannot omit it when it is the subject (e.g., “The book that is on the table”).

  6. Are relative clauses always placed immediately after the noun they modify?

    Yes, relative clauses should be placed immediately after the noun they modify to avoid confusion and maintain clarity.

  7. What are reduced relative clauses, and how do they work?

    Reduced relative clauses are shortened forms where the relative pronoun and auxiliary verb are omitted, typically when the pronoun is the subject. For example, “The car being repaired is mine” is a reduced form of “The car that is being repaired is mine.”

  8. How do I use prepositions in relative clauses correctly?

    Prepositions can be placed either before the relative pronoun (formal) or at the end of the clause (informal). For example, “The person to whom I spoke” (formal) or “The person who I spoke to” (informal).

Conclusion

Mastering defining and non-defining relative clauses is essential for clear and effective communication in English. Understanding the difference between these clauses, along with their punctuation and usage rules, will significantly improve your writing and speaking skills.

Remember to pay close attention to whether the information is essential or extra, and punctuate accordingly. Practice regularly, and you’ll soon be using relative clauses with confidence.