Infinitive phrases are groups of words that begin with an infinitive, usually to + the base form of a verb, and may include objects, complements, or modifiers. For example, in the sentence She wants to learn English quickly, to learn English quickly is an infinitive phrase.
An infinitive phrase can perform different grammatical functions in a sentence. It may act as a noun, adjective, or adverb, depending on how it is used. For example, an infinitive phrase can be the subject of a sentence, complete the meaning of a verb, describe a noun, or explain the purpose of an action.
In this guide, you will learn what infinitive phrases are, how they are formed, how to identify them, and how they function in English sentences. You will also see plenty of infinitive phrase examples and learn how to distinguish infinitive phrases from similar structures such as prepositional phrases.
Table of Contents
What Is an Infinitive Phrase?
An infinitive phrase is a group of words that begins with an infinitive and includes any objects, complements, or modifiers connected to it. An infinitive is usually formed with to + the base form of a verb, such as to read, to write, to learn, or to speak.
The basic structure of an infinitive phrase is:
to + base verb + object/complement/modifier
For example:
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to read a book
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to learn English
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to speak confidently
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to finish the project on time
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to become a successful writer
In the sentence:
She wants to learn English quickly.
The words to learn English quickly form an infinitive phrase. To learn is the infinitive, English is its object, and quickly modifies the verb learn.
An infinitive phrase acts as a single grammatical unit in a sentence. Depending on its purpose, the entire phrase can function like a noun, adjective, or adverb.
Consider these examples:
To learn a new language takes time.
Here, to learn a new language functions as a noun and serves as the subject of the sentence.
She has a lot of work to finish today.
Here, to finish today describes work, so the infinitive phrase functions like an adjective.
He went to the library to study for his exam.
Here, to study for his exam explains why he went to the library, so the infinitive phrase functions like an adverb.
Infinitive vs. Infinitive Phrase
An infinitive consists of to followed by the base form of a verb, while an infinitive phrase contains the infinitive together with other words that complete or modify its meaning.
| Infinitive | Infinitive Phrase |
|---|---|
| to read | to read a novel |
| to write | to write an email carefully |
| to learn | to learn English online |
| to travel | to travel around the world |
| to become | to become a better speaker |
For example, to write is an infinitive, while to write a professional email is an infinitive phrase.
Understanding this difference makes it easier to recognize infinitive phrases and determine the role they play in a sentence.
Structure of an Infinitive Phrase
An infinitive phrase is built around an infinitive, which usually consists of to + the base form of a verb. The infinitive may then be followed by an object, complement, modifier, or a combination of these elements.
The general structure is:
Infinitive Phrase = to + base verb + object/complement/modifier
Not every infinitive phrase contains all of these elements. Its structure depends on the verb and the information needed to complete its meaning.
1. Infinitive + Object
When the verb in the infinitive takes an object, the object becomes part of the infinitive phrase.
Structure:
to + verb + object
Examples:
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to read a book
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to buy a new car
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to learn English
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to complete the assignment
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to help my friend
In the sentence:
I want to learn English.
The infinitive phrase is to learn English. The word English is the object of the infinitive to learn.
2. Infinitive + Complement
Some infinitives are followed by a complement that completes their meaning.
Structure:
to + verb + complement
Examples:
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to become a doctor
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to be successful
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to remain calm
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to become more confident
For example:
Her goal is to become a doctor.
In to become a doctor, the noun phrase a doctor is a complement that completes the meaning of become.
3. Infinitive + Modifier
An infinitive can also be accompanied by a modifier that provides additional information about the action.
Structure:
to + verb + modifier
Examples:
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to speak clearly
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to work efficiently
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to arrive early
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to respond politely
For example:
She tried to speak clearly.
The adverb clearly modifies speak and is part of the infinitive phrase to speak clearly.
4. Infinitive + Object + Modifier
An infinitive phrase may contain both an object and one or more modifiers.
Structure:
to + verb + object + modifier
Examples:
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to finish the project on time
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to answer the question correctly
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to learn English quickly
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to complete the work before Friday
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to explain the lesson clearly
For example:
We need to finish the project on time.
The complete infinitive phrase is to finish the project on time. Here, the project is the object of finish, while on time modifies the action.
Infinitive Phrase Structure at a Glance
| Structure | Example |
|---|---|
| to + verb + object | to read a book |
| to + verb + complement | to become a teacher |
| to + verb + modifier | to speak confidently |
| to + verb + object + modifier | to finish the work quickly |
The infinitive is the central part of the phrase, while the words that follow it add or complete its meaning. When identifying an infinitive phrase, look for the infinitive first and then determine which words belong with it.
Examples of Infinitive Phrases
Infinitive phrases are common in everyday English. They can express actions, goals, plans, purposes, and ideas while performing different grammatical functions within a sentence.
Here are some common examples of infinitive phrases:
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to learn a new language
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to finish the assignment
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to speak English fluently
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to travel around the world
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to become a successful teacher
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to help people in need
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to arrive at work on time
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to prepare for the exam
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to improve your writing skills
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to find a better job
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to save enough money
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to complete the project successfully
Notice that each phrase begins with an infinitive such as to learn, to finish, or to speak. Other words are added to complete or modify the meaning of the infinitive.
Infinitive Phrase Examples in Sentences
Here are some examples showing how infinitive phrases appear in complete sentences:
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To learn English fluently requires regular practice.
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She wants to improve her writing skills.
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His dream is to travel around the world.
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We have several assignments to complete before Friday.
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She went to the library to prepare for her exam.
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They decided to start a new business.
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He needs a quiet place to study in the evening.
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I woke up early to catch the first bus.
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To become a good writer takes time and practice.
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The students are eager to learn something new.
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She saved money to buy a new laptop.
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We need someone to organize the event.
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He promised to finish the work on time.
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They traveled to London to visit their relatives.
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My goal is to speak English more confidently.
In each example, the bold words form an infinitive phrase. However, these phrases do not all perform the same job. Some function like nouns, some modify nouns, and others explain the purpose or reason for an action.
For example:
To exercise regularly is good for your health.
Here, to exercise regularly is the subject of the sentence and functions as a noun.
She needs a book to read on the train.
Here, to read on the train modifies the noun book.
He exercises every morning to stay healthy.
Here, to stay healthy explains why he exercises and functions as an adverb.
These different functions are important because the role of an infinitive phrase depends on how the entire phrase is used in the sentence, not simply on the fact that it begins with to + verb.
Functions of Infinitive Phrases
An infinitive phrase can perform different grammatical functions depending on how it is used in a sentence. The three main functions of infinitive phrases are as nouns, adjectives, and adverbs.
Understanding these functions can help you identify what an infinitive phrase is doing rather than simply recognizing its to + verb structure.
1. Infinitive Phrase as a Noun
An infinitive phrase functions as a noun when it names an action, activity, or idea. Like other nouns and noun phrases, it can serve as the subject, object, or complement of a sentence.
To learn a new language takes time.
Here, to learn a new language is the subject of the sentence.
She wants to learn a new language.
Here, to learn a new language completes the meaning of the verb wants.
Her goal is to learn a new language.
Here, to learn a new language follows the linking verb is and identifies what her goal is.
More examples include:
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To exercise every day is good for your health.
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I hope to visit Canada next year.
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His ambition is to become a successful writer.
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They decided to postpone the meeting.
2. Infinitive Phrase as an Adjective
An infinitive phrase functions like an adjective when it modifies or provides more information about a noun or pronoun. It usually appears after the word it modifies.
She has a report to finish before Friday.
The infinitive phrase to finish before Friday modifies the noun report. It tells us which task or obligation is associated with the report.
Consider another example:
We need a place to hold the meeting.
The phrase to hold the meeting modifies place by explaining its intended use.
More examples include:
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I have several emails to answer today.
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She needs a book to read on the plane.
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We have a lot of work to complete this week.
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He was the first student to finish the test.
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They are looking for someone to lead the project.
A useful way to recognize this function is to ask whether the infinitive phrase gives additional information about a noun or pronoun.
3. Infinitive Phrase as an Adverb
An infinitive phrase functions like an adverb when it modifies a verb, adjective, or sometimes another adverb. It often explains why an action happens or the purpose for which something is done.
She went to the library to study for her exam.
The phrase to study for her exam explains why she went to the library.
He exercises every morning to stay healthy.
Here, to stay healthy expresses the purpose of exercising.
Infinitive phrases can also modify adjectives:
I am happy to see you again.
Here, to see you again helps complete the meaning of the adjective happy.
More examples include:
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She called me to ask a question.
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We left early to avoid the traffic.
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He saved money to buy a new computer.
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They met after work to discuss the project.
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I was surprised to hear the news.
Noun, Adjective, and Adverb Functions at a Glance
| Function | What the Infinitive Phrase Does | Example |
|---|---|---|
| Noun | Acts as a subject, object, or complement | To travel abroad is exciting. |
| Adjective | Modifies a noun or pronoun | I need a bag to carry my books. |
| Adverb | Modifies a verb or adjective, often expressing purpose or reason | She called to invite us to dinner. |
The easiest way to determine the function of an infinitive phrase is to examine its relationship with the other words in the sentence. If it occupies a noun position, it functions as a noun; if it modifies a noun, it functions as an adjective; and if it modifies a verb or adjective, it functions as an adverb.
Conclusion
Infinitive phrases are an important part of English grammar. They are built around an infinitive, usually to + the base form of a verb, and may also contain objects, complements, and modifiers. For example, to learn English, to finish the work on time, and to speak more confidently are all infinitive phrases.
Depending on their role in a sentence, infinitive phrases can function as nouns, adjectives, or adverbs. They can serve as subjects and complements, modify nouns, complete the meaning of verbs, or explain the purpose of an action. Looking at how the complete phrase relates to the rest of the sentence is the best way to determine its function.
To become more comfortable with infinitive phrases, practice identifying to + base verb, finding all the words that belong to the phrase, and determining its grammatical function. With regular practice, you will be able to recognize and use infinitive phrases more accurately in both speaking and writing.