Relative Clauses: Mastering Definition & Usage in English Grammar

Relative clauses are essential components of English grammar, adding depth and complexity to sentences. They allow us to provide additional information about nouns or pronouns, enhancing clarity and precision in our writing and speech.

Understanding how to use relative clauses correctly is crucial for effective communication, whether you’re writing an academic paper, crafting a business proposal, or simply engaging in everyday conversation. This article will provide a comprehensive guide to relative clauses, covering their definition, structure, types, usage rules, common mistakes, and advanced topics.

By mastering this grammatical concept, you can significantly improve your English language skills. This guide is suitable for English language learners of all levels, from beginners to advanced speakers and writers.

Table of Contents

• Definition of Relative Clauses
• Structural Breakdown of Relative Clauses
• Types of Relative Clauses
  • Defining Relative Clauses (Essential)
  • Non-Defining Relative Clauses (Non-Essential)
  • Contact Relative Clauses
• Examples of Relative Clauses
• Usage Rules for Relative Clauses
• Common Mistakes with Relative Clauses
• Practice Exercises
• Advanced Topics in Relative Clauses
  • Reduced Relative Clauses
  • Relative Clauses with Prepositions
• Frequently Asked Questions (FAQ)
• Conclusion

Definition of Relative Clauses

A relative clause is a type of subordinate clause that modifies a noun or pronoun. It functions as an adjective, providing additional information about the noun or pronoun it modifies, also known as the antecedent. Relative clauses are introduced by relative pronouns (who, whom, which, that) or relative adverbs (where, when, why). They are essential for adding detail and specificity to sentences, making them more informative and engaging. Understanding relative clauses is crucial for both reading comprehension and effective writing.

The primary function of a relative clause is to identify or describe the noun or pronoun it modifies. It essentially answers the question “which one?” or “what kind?” about the antecedent. Without relative clauses, we would have to use multiple shorter sentences to convey the same information, making our writing less concise and more repetitive. For instance, instead of saying “The book that I borrowed from the library is due next week,” we would have to say “I borrowed the book from the library. The book is due next week.” This demonstrates how relative clauses streamline our sentences and enhance their clarity.

Structural Breakdown of Relative Clauses

The basic structure of a relative clause consists of a relative pronoun or adverb followed by a subject and verb (although the subject can sometimes be omitted, especially in reduced relative clauses). The relative pronoun or adverb connects the relative clause to the main clause and also serves a grammatical function within the relative clause itself, such as subject, object, or complement. The relative clause is always dependent on the main clause and cannot stand alone as a complete sentence.

Here’s a breakdown of the structural elements:

• Antecedent: The noun or pronoun that the relative clause modifies.
• Relative Pronoun/Adverb: The word that introduces the relative clause (who, whom, which, that, where, when, why).
• Subject: The noun or pronoun that performs the action in the relative clause.
• Verb: The action word in the relative clause.
• Object/Complement: The noun or pronoun that receives the action of the verb or completes the meaning of the verb.

Consider the sentence: “The student who studies diligently will succeed.” In this example, “student” is the antecedent, “who” is the relative pronoun, “studies” is the verb, and “diligently” is an adverb modifying the verb. The entire clause “who studies diligently” modifies the noun “student.”

Types of Relative Clauses

Relative clauses can be broadly classified into two main types: defining (or essential) relative clauses and non-defining (or non-essential) relative clauses. Additionally, we’ll explore contact relative clauses.

Defining Relative Clauses (Essential)

Defining relative clauses, also known as essential relative clauses, provide information that is necessary to identify the noun or pronoun they modify. Without the defining relative clause, the meaning of the sentence would be unclear or incomplete. These clauses are not set off by commas because they are integral to the meaning of the sentence.

For example, in the sentence “The book that I ordered online arrived today,” the relative clause “that I ordered online” is essential because it specifies which book we are talking about. If we removed the relative clause, the sentence would become “The book arrived today,” which is too vague. The reader would not know which book is being referenced.

Non-Defining Relative Clauses (Non-Essential)

Non-defining relative clauses, also known as non-essential relative clauses, provide additional information about the noun or pronoun they modify, but this information is not essential for identifying it. The sentence would still make sense if the non-defining relative clause were removed. These clauses are always set off by commas because they provide supplementary information.

For example, in the sentence “My sister, who lives in London, is a doctor,” the relative clause “who lives in London” provides extra information about the sister but is not necessary to identify her. We already know who we are talking about (my sister). Therefore, the clause is set off by commas.

Contact Relative Clauses

Contact relative clauses are relative clauses where the relative pronoun (who, whom, which, that) is omitted. This is possible when the relative pronoun functions as the object of the relative clause, not the subject. Contact clauses are primarily used in defining relative clauses to make the sentence more concise without sacrificing clarity.

For example, instead of saying “The car that I bought is red,” we can say “The car I bought is red.” In this case, “that” is the object of the verb “bought,” so it can be omitted. However, we cannot omit the relative pronoun if it is the subject of the verb, as in “The student who studies diligently will succeed.”

Examples of Relative Clauses

The following tables provide extensive examples of relative clauses, categorized by type and relative pronoun/adverb. These examples will help you understand how relative clauses are used in different contexts and how they function within sentences.

Table 1: Examples of Defining Relative Clauses

This table showcases examples of defining relative clauses using various relative pronouns and adverbs. These clauses are essential for identifying the noun they modify.

Sentence	Relative Clause	Relative Pronoun/Adverb
The man who helped me is a doctor.	who helped me	who
The book that I borrowed is very interesting.	that I borrowed	that
The house which is on the hill is very old.	which is on the hill	which
The person whom I admire most is my mother.	whom I admire most	whom
The city where I was born is very crowded.	where I was born	where
The day when I met her was unforgettable.	when I met her	when
The reason why I am here is important.	why I am here	why
The dog that barked all night kept me awake.	that barked all night	that
The movie which we watched last night was scary.	which we watched last night	which
The student who won the prize is very talented.	who won the prize	who
The song that they played was my favorite.	that they played	that
The restaurant where we ate dinner was excellent.	where we ate dinner	where
The time when the concert starts is 8 PM.	when the concert starts	when
The problem why I am struggling is complex.	why I am struggling	why
The project that I’m working on is challenging.	that I’m working on	that
The teacher who inspires me most is Ms. Johnson.	who inspires me most	who
The country where I want to travel is Japan.	where I want to travel	where
The year when I graduated was 2020.	when I graduated	when
The strategy why we succeeded was teamwork.	why we succeeded	why
The solution that we found was effective.	that we found	that
The author who wrote that book is famous.	who wrote that book	who
The game which we played was fun.	which we played	which
The actor whom everyone admires is very humble.	whom everyone admires	whom
The park where we had a picnic is beautiful.	where we had a picnic	where
The moment when I realized my mistake was embarrassing.	when I realized my mistake	when
The excuse why he was late was unconvincing.	why he was late	why

Table 2: Examples of Non-Defining Relative Clauses

This table illustrates non-defining relative clauses, which provide extra information that is not essential to the meaning of the sentence. These clauses are always set off by commas.

Sentence	Relative Clause	Relative Pronoun/Adverb
My brother, who is a teacher, lives in New York.	who is a teacher	who
The Eiffel Tower, which is in Paris, is a famous landmark.	which is in Paris	which
My hometown, where I grew up, is a small village.	where I grew up	where
The movie, which I saw last week, was excellent.	which I saw last week	which
My car, which is very old, still runs well.	which is very old	which
My neighbor, who is a lawyer, gave me some advice.	who is a lawyer	who
The museum, which is free on Sundays, is very popular.	which is free on Sundays	which
My favorite restaurant, where I always order pizza, is closed today.	where I always order pizza	where
The concert, which starts at 8 PM, is sold out.	which starts at 8 PM	which
My best friend, who is a writer, just published a book.	who is a writer	who
The park, which is near my house, is very peaceful.	which is near my house	which
My cat, who loves to sleep, is very lazy.	who loves to sleep	who
The company, which is based in California, is very successful.	which is based in California	which
My grandmother, who is 90 years old, is still very active.	who is 90 years old	who
The library, which has a large collection of books, is a great resource.	which has a large collection of books	which
My uncle, who is an engineer, helped me fix my car.	who is an engineer	who
The school, which has a good reputation, is very competitive.	which has a good reputation	which
My favorite coffee shop, where I study, is always busy.	where I study	where
The festival, which is held every summer, attracts many tourists.	which is held every summer	which
My cousin, who is a musician, plays the piano.	who is a musician	who
The beach, which is close to my house, is very crowded in summer.	which is close to my house	which
My dog, who loves to play fetch, is very energetic.	who loves to play fetch	who
The university, which is known for its research, is highly regarded.	which is known for its research	which
My favorite bakery, where I buy bread every day, is very popular.	where I buy bread every day	where
The holiday, which I celebrate with my family, is very special.	which I celebrate with my family	which

Table 3: Examples of Contact Relative Clauses

This table presents examples of contact relative clauses, where the relative pronoun is omitted. Remember that the relative pronoun can only be omitted when it functions as the object of the clause.

Sentence	Relative Clause (with omitted pronoun)	Full Relative Clause (with pronoun)
The book I read was fascinating.	I read	that I read
The car he bought is very expensive.	he bought	that he bought
The movie we watched was boring.	we watched	that we watched
The person I met was very kind.	I met	whom I met
The song she wrote became a hit.	she wrote	that she wrote
The project they completed was successful.	they completed	that they completed
The idea I suggested was rejected.	I suggested	that I suggested
The food we ordered was delicious.	we ordered	that we ordered
The job he applied for is very competitive.	he applied for	that he applied for
The course I’m taking is challenging.	I’m taking	that I’m taking
The problem we faced was difficult.	we faced	that we faced
The solution they found was innovative.	they found	that they found
The advice she gave was helpful.	she gave	that she gave
The support we received was invaluable.	we received	that we received
The effort he made was commendable.	he made	that he made
The progress they achieved was significant.	they achieved	that they achieved
The mistake I made was costly.	I made	that I made
The lesson we learned was important.	we learned	that we learned
The skill he acquired was valuable.	he acquired	that he acquired
The experience I gained was enriching.	I gained	that I gained
The information she provided was accurate.	she provided	that she provided
The opportunity they offered was exciting.	they offered	that they offered
The challenge we overcame was rewarding.	we overcame	that we overcame
The goal he achieved was ambitious.	he achieved	that he achieved
The dream I pursued was fulfilling.	I pursued	that I pursued

Usage Rules for Relative Clauses

Using relative clauses correctly involves adhering to specific rules regarding the choice of relative pronouns/adverbs and the placement of commas. Understanding these rules will help you construct grammatically correct and clear sentences.

• Use who and whom for people: Who is used as the subject of the relative clause (e.g., “The man who is speaking is my boss”). Whom is used as the object of the relative clause (e.g., “The person whom I called was not available”).
• Use which for things: Which is used to refer to inanimate objects or animals (e.g., “The car which I bought is red”).
• Use that for people or things in defining relative clauses: That can often be used interchangeably with who or which in defining relative clauses (e.g., “The book that I read was interesting”). However, that cannot be used in non-defining relative clauses.
• Use where for places: Where is used to refer to locations (e.g., “The city where I live is very lively”).
• Use when for times: When is used to refer to specific times or occasions (e.g., “The day when I met her was special”).
• Use why for reasons: Why is used to refer to the reason for something (e.g., “The reason why I am here is important”).
• Use commas with non-defining relative clauses: Non-defining relative clauses are always set off by commas (e.g., “My mother, who is a teacher, is very dedicated”).
• Do not use commas with defining relative clauses: Defining relative clauses are not set off by commas (e.g., “The book that I borrowed is due next week”).
• Omit relative pronouns in contact clauses: When the relative pronoun is the object of the relative clause, it can be omitted, especially in defining relative clauses (e.g., “The car I bought is red”).

It’s also important to ensure that the relative pronoun or adverb agrees with its antecedent in number and gender. For example, if the antecedent is singular, the verb in the relative clause should also be singular.

Common Mistakes with Relative Clauses

Several common mistakes can occur when using relative clauses. Being aware of these errors can help you avoid them and improve the accuracy of your writing.

Table 4: Common Mistakes with Relative Clauses

This table illustrates common mistakes made when using relative clauses, providing both incorrect and correct examples to highlight the differences.

Incorrect	Correct	Explanation
The man who I saw him was tall.	The man whom I saw was tall.	Using “who” when “whom” is needed as the object of the verb.
The book, that I read, was interesting.	The book that I read was interesting.	Using “that” in a non-defining relative clause (should be “which”).
My sister, that lives in London, is a doctor.	My sister, who lives in London, is a doctor.	Using “that” in a non-defining relative clause (should be “who”).
The house which it is on the hill is old.	The house which is on the hill is old.	Unnecessary use of “it” after “which.”
The reason because I am late is traffic.	The reason why I am late is traffic.	Using “because” instead of “why” to introduce a relative clause of reason.
The city where I live it is crowded.	The city where I live is crowded.	Unnecessary use of “it” after “where.”
The car who I bought is red.	The car which I bought is red.	Using “who” to refer to an object (should be “which”).
My friend, which is a teacher, is very smart.	My friend, who is a teacher, is very smart.	Using “which” to refer to a person (should be “who”).
The day when I met her it was sunny.	The day when I met her was sunny.	Unnecessary use of “it” after “when.”
The person who I admire him is my father.	The person whom I admire is my father.	Using “who” when “whom” is needed, and unnecessary use of “him.”
The book, which I read it last year, was great.	The book, which I read last year, was great.	The unnecessary pronoun “it” should be removed.
The restaurant where I ate there was expensive.	The restaurant where I ate was expensive.	The unnecessary adverb “there” should be removed.
The project that I worked on it was successful.	The project that I worked on was successful.	The unnecessary pronoun “it” should be removed.
The song who she sang was beautiful.	The song that she sang was beautiful.	“Who” should be replaced by “that” as it refers to a song.
The reason why he left it was a secret.	The reason why he left was a secret.	The unnecessary pronoun “it” should be removed.
The city where I visited there was amazing.	The city where I visited was amazing.	The unnecessary adverb “there” should be removed.
The movie which we saw it was long.	The movie which we saw was long.	The unnecessary pronoun “it” should be removed.
The problem that I have it is complex.	The problem that I have is complex.	The unnecessary pronoun “it” should be removed.
The solution who they found was innovative.	The solution that they found was innovative.	“Who” should be replaced by “that” as it refers to a solution.
The student who he studies hard will succeed.	The student who studies hard will succeed.	The unnecessary pronoun “he” should be removed.

Practice Exercises

The following exercises will help you practice using relative clauses correctly. Each exercise focuses on a specific aspect of relative clause usage, such as choosing the correct relative pronoun/adverb or identifying defining and non-defining relative clauses.

Exercise 1: Choose the correct relative pronoun or adverb.

Select the correct relative pronoun or adverb to complete each sentence.

Table 5: Practice Exercise 1

Question	Options	Answer
The book _______ I borrowed from the library is due next week.	(a) who (b) which (c) where	(b) which
The man _______ helped me fix my car is a mechanic.	(a) who (b) which (c) where	(a) who
The city _______ I was born is very crowded.	(a) when (b) which (c) where	(c) where
The day _______ I graduated was unforgettable.	(a) who (b) when (c) which	(b) when
The reason _______ I am studying English is to travel.	(a) who (b) why (c) where	(b) why
The movie _______ we watched last night was very scary.	(a) who (b) which (c) where	(b) which
The student _______ won the award is very talented.	(a) who (b) which (c) where	(a) who
The restaurant _______ we ate dinner was excellent.	(a) when (b) which (c) where	(c) where
The time _______ the concert starts is 8 PM.	(a) who (b) when (c) which	(b) when
The problem _______ I am facing is very complex.	(a) who (b) why (c) which	(c) which

Exercise 2: Identify whether the relative clause is defining or non-defining.

Determine whether each relative clause is defining (essential) or non-defining (non-essential).

Table 6: Practice Exercise 2

Sentence	Type of Relative Clause
The book that I borrowed from the library is due next week.	Defining
My sister, who lives in London, is a doctor.	Non-Defining
The car which is parked outside is mine.	Defining
My hometown, where I grew up, is a small village.	Non-Defining
The movie that I saw last night was excellent.	Defining
My cat, who loves to sleep, is very lazy.	Non-Defining
The company which is based in California is very successful.	Defining
My grandmother, who is 90 years old, is still very active.	Non-Defining
The library that has a large collection of books is a great resource.	Defining
My uncle, who is an engineer, helped me fix my car.	Non-Defining

Exercise 3: Rewrite the sentences using contact relative clauses where possible.

Rewrite the following sentences, omitting the relative pronoun to create contact relative clauses.

Table 7: Practice Exercise 3

Original Sentence	Rewritten Sentence (Contact Clause)
The book that I read was fascinating.	The book I read was fascinating.
The car that he bought is very expensive.	The car he bought is very expensive.
The movie that we watched was boring.	The movie we watched was boring.
The person whom I met was very kind.	The person I met was very kind.
The song that she wrote became a hit.	The song she wrote became a hit.
The project that they completed was successful.	The project they completed was successful.
The idea that I suggested was rejected.	The idea I suggested was rejected.
The food that we ordered was delicious.	The food we ordered was delicious.
The job that he applied for is very competitive.	The job he applied for is very competitive.
The course that I’m taking is challenging.	The course I’m taking is challenging.

Advanced Topics in Relative Clauses

For advanced learners, there are more complex aspects of relative clauses to explore, such as reduced relative clauses and relative clauses with prepositions.

Reduced Relative Clauses

Reduced relative clauses are shortened forms of relative clauses where the relative pronoun and auxiliary verb (e.g., is, are, was, were) are omitted. This reduction is possible when the relative clause contains a form of the verb “be” followed by a participle (present or past). Reduced relative clauses make sentences more concise and fluent.

For example, “The book that is lying on the table is mine” can be reduced to “The book lying on the table is mine.” Similarly, “The car that was damaged in the accident is being repaired” can be reduced to “The car damaged in the accident is being repaired.”

Relative Clauses with Prepositions

Relative clauses with prepositions involve placing a preposition either before the relative pronoun or at the end of the relative clause. The choice of placement can affect the formality of the sentence.

For example, “The house in which I live is very old” is a more formal way of saying “The house which I live

in is very old” or “The house that I live in is very old.” In less formal contexts, the preposition is typically placed at the end of the relative clause. When using “which” or “whom” after a preposition, “that” cannot be used.

Frequently Asked Questions (FAQ)

This section addresses some frequently asked questions about relative clauses, providing quick and clear answers to common queries.

Conclusion

Mastering relative clauses is essential for enhancing your English language skills. By understanding their definition, structure, types, usage rules, and common mistakes, you can construct clearer, more precise, and more engaging sentences.

Practice the exercises provided to reinforce your understanding and continue to refine your skills. Whether you are writing academic papers, business proposals, or simply engaging in everyday conversation, a solid grasp of relative clauses will significantly improve your communication abilities.

Keep practicing and exploring advanced topics to further elevate your proficiency in English grammar.