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What Is an Infinitive? | Definition, Examples & Uses

Verbs updated on  February 5, 2024 7 min read
In English, an infinitive is a verb form that is the same as the base or dictionary form. It’s often preceded by “to” (e.g., “to study,” “to run”).

Infinitives have many uses, including acting as an object or a subject instead of the main verb.

Infinitive examples
To err is human.
We need to talk.

What are infinitive verbs?

Infinitives in English are verb forms that are the same as the base or dictionary form, and they can function as subjects, nouns, adverbs, and adjectives. There are two types of infinitive: the full infinitive and the bare infinitive.

Full infinitives

Full infinitives are also known as to-infinitives because they consist of “to” followed by the base form of the verb (e.g., “to sing”). Full infinitives are more commonly used than bare infinitives.

A number of verbs (e.g., “beg,” “demand,” and “plan”) are always followed by the full infinitive rather than the bare infinitive when an infinitive is needed.

Examples
We arranged meet on Wednesday.
We arranged to meet on Wednesday.

I forgot bring my homework.
I forgot to bring my homework.

Bare infinitives

Bare infinitives (aka zero infinitives) are simply the base form of the verb without “to” (e.g., “sing”).

The uses of bare infinitives are more limited than those of full infinitives. Bare infinitives commonly follow modal verbs (and the auxiliary verb “do”), verbs of perception, and a few other verbs (e.g., “let” and “make”).

Bare infinitive examples
We must stop him.
I saw her catch the ball.
My parents made me wash the car.

Note
The verb after a modal verb (or the auxiliary verb “do”) is both the main verb and an infinitive. You can determine whether a main verb is an infinitive by whether it changes form when the subject changes.

  I read books in Japanese. → She reads books in Japanese.
  [this verb changes form, so it is not an infinitive]

  I can read books in Japanese. → She can read books in Japanese.
  [this verb doesn’t change form, so it is an infinitive]

Some verbs can either be followed by a bare infinitive or a full infinitive.

Bare infinitive and full infinitive examples
Help me carry the shopping.
Help me to carry the shopping.

Infinitive phrases

When an infinitive is followed by complements (e.g., direct objects) or modifiers (e.g., adverbs), the group of words is known as an infinitive phrase.

Infinitive phrases can be used in the same ways as full infinitives and bare infinitives, and both full infinitives and bare infinitives can appear in infinitive phrases.

Infinitive phrase examples
I went to watch the sunrise.
The teacher asked the class to listen carefully.
She can paint beautiful pictures very quickly.

How to use infinitives

Infinitives are very common and have many uses. They can perform all the following functions:

As the subject

You will sometimes see full infinitives used as the subject of a sentence. In this case, they function as nouns referring to the action in general.

Infinitive as subject examples
To live is the greatest adventure.
To try to convince him is pointless.

As an object

Full infinitives also function as nouns when being used as the direct object of the main verb.

Infinitive as direct object examples
We need to run faster.
The children wanted to play.

As a subject complement

Infinitives can act as subject complements—which describe, define, or identify the subject—when following linking verbs (e.g., “be,” “seem”).

Infinitive as direct object examples
My ambition is to become a physicist.
The dog seems to want a treat.

As an adverb

Infinitives can function as adverbs modifying the main verb.

The infinitive won’t necessarily directly follow the main verb, but you can determine whether it’s functioning as an adverb by asking the following questions:

  • Is it explaining why the action described by the main verb happened or is happening?
  • Can the “to” in the infinitive be replaced with “in order to” with no change in meaning?

Infinitive as an adverb examples
I learned programming [in order] to get a better job.
She made a cup of tea [in order] to calm herself down.

Note that “in order to” can sometimes provide necessary clarity, but “to” is sufficient most of the time.

Note
If an infinitive or infinitive phrase is used as an adverb at the beginning of the sentence, it should be followed by a comma. In other cases, no comma is needed before or after the infinitive.

To impress Gloria, Dean learned ballroom dancing.
Dean learned ballroom dancing to impress Gloria.

As an adjective

When an infinitive modifies a noun, it’s behaving as an adjective describing the noun (e.g., its purpose or characteristics).

Infinitive as an adjective examples
We built a house to live in.
The right thing to do isn’t always clear.

Other uses

Infinitives can also follow adjectives to provide further detail.

Infinitive and adjective examples
This book is difficult to understand.
It’s reassuring to know you’re here.

Infinitives can follow adjectives or nouns used with “too” or “enough” to express the intended meaning.

Infinitive examples
Sally is too young to watch that movie.
We have enough food to feed an army!

You can also use infinitives with relative pronoun phrases. In phrases using the relative pronouns “who/whom,” “what,” “when,” “where,” and “how,” use a full infinitive.

Infinitive with a relative pronoun examples
I don’t know who to ask.
Teach me how to cook.

In certain questions using “why,” the bare infinitive is used. These questions are usually rhetorical, suggestions phrased as questions, or questions passing judgment on an action rather than interrogative questions.

Infinitive with "why" examples
Why worry about things you can’t change?
Why not take a break?
Why say something you don’t mean?

Other infinitive forms

Although infinitives don’t change their form for different subjects, they can change to form the perfect infinitive, continuous infinitive, and perfect continuous infinitive as well as the passive infinitive. These constructions also use auxiliary verbs.

Infinitive examples
I had hoped to have finished my work by now.
That person seems to be waving at you.
You should have been listening.
The plants need to be watered every week.

Split infinitives

A split infinitive is a full infinitive that has words (usually adverbs) separating “to” and the verb (e.g., “to quickly run”).

The traditional idea that split infinitives are incorrect or “bad grammar” stems from historic attempts to make English more like Latin (in Latin, infinitives are one word and cannot be split).

Splitting an infinitive is sometimes incorrect or unnecessary, but it can provide emphasis or clarity in some cases and doesn’t need to be avoided entirely.

Split infinitive example
He proceeded to slowly walk to the cafeteria.
He proceeded to walk slowly to the cafeteria.

The first sentence above (with the split infinitive) is acceptable in informal contexts, but it can be easily reworded to avoid the split infinitive without change in meaning or emphasis. Rewording when possible is especially advisable in formal writing.

Split infinitive example
You must put yourself in someone else’s shoes to truly understand them.
You must put yourself in someone else’s shoes truly to understand them.
You must put yourself in someone else’s shoes to understand them truly.

In the above example, splitting the infinitive is the best option because the alternatives don’t convey the meaning as well or as accurately.

Gerunds and infinitives

Gerunds use the “-ing” form of the verb (e.g., “jumping”). While infinitives have other uses, gerunds only function as nouns.

Both infinitives and gerunds can be used as the subject of a sentence; however, it’s more common to use a gerund as the subject. A gerund will often sound more natural, while an infinitive might sound formal, abstract, or unusual.

Gerunds and infinitives as subjects examples
Becoming president is her ambition. [preferred]
To become president is her ambition. [acceptable]

Exercising is good for you. [preferred]
To exercise is good for you. [unusual]

Note
The “-ing” form is not always a gerund; it’s also the present participle, which forms the continuous tenses and can be used as an adjective.

Gerunds and infinitives can both function as direct objects, but they’re not always interchangeable. Certain verbs can only take infinitives as direct objects, while other verbs can only take gerunds. Some verbs can take either.

Gerunds and infinitives as direct objects examples
I like swimming.
I like to swim.

I enjoy swimming.
I enjoy to swim.

I promise calling.
I promise to call.

Only gerunds can follow prepositions (except for the prepositions “but” and “except,” which are often followed by infinitives).

Gerunds and prepositions examples
The headmaster scolded the children for talking during the lesson.
He apologized by making dinner.
I have no choice but to leave.

Do you want to know more about common mistakes, commonly confused words, or other language topics? Check out some of our other language articles full of examples and quizzes.


Common mistakes

Commonly confused words

Rhetoric

Whoa or woah

Advisor vs adviser

Metonymy

Theirs or their's

Accept vs except

Synecdoche

Ours or our's

Affect vs effect

Verbal irony

Forty or fourty

Among vs between

Irony

Sence or sense

Anymore vs any more

Grawlix


Frequently asked questions about the infinitive

What is a bare infinitive?

A bare infinitive is the same as the base or dictionary form of the verb (e.g., “eat”), while a full infinitive is the base form of the verb preceded by “to” (e.g., “to eat”).

Bare infinitives often follow modal verbs (e.g., “we can fly”), the auxiliary verb “do” (e.g., “don’t touch”), and sense verbs (e.g., “I saw him run”).

There are a few verbs, such as “let” and “make,” that must be followed by bare infinitives instead of full infinitives (e.g., “let me try” not “let me to try”).

Infinitives have many uses, including functioning as subjects, direct objects, adjectives, and adverbs.

What is a full infinitive?

A full infinitive is the base form of the verb preceded by “to” (e.g., “to drink”). A bare infinitive, on the other hand, is simply the base form of the verb without “to” (e.g., “drink”).

Infinitives can be used as subjects, direct objects, adverbs, and adjectives. Full infinitives are more common than bare infinitives, and several verbs can only be followed by full infinitives (e.g., “I promise to visit” not “I promise visit”).

What’s the difference between infinitives and prepositional phrases?

Both infinitives and prepositional phrases can begin with “to.” However, an infinitive is “to” plus a verb, while “to” in a prepositional phrase is followed by a noun or pronoun.

For example, in “I want to take her to the cinema,” “to take” is an infinitive and “to the cinema” is a prepositional phrase.

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Sophie Shores

Sophie has a BA in English Literature, an MA in Publishing, and a passion for great writing. She’s taught English overseas and has experience editing both business and academic writing.

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