What Is an Infinitive? | Definition, Examples & Uses
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.
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.
- 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”).
I saw her catch the ball.
My parents made me wash the car.
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.
- 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.
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.
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.
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”).
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?
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.
- 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).
The right thing to do isn’t always clear.
Other uses
Infinitives can also follow adjectives to provide further detail.
It’s reassuring to know you’re here.
Infinitives can follow adjectives or nouns used with “too” or “enough” to express the intended meaning.
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.
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.
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.
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.
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.
- 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.
To become president is her ambition. [acceptable]
Exercising is good for you. [preferred]
To exercise is good for you. [unusual]
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.
- 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).
He apologized by making dinner.
I have no choice but to leave.
Frequently asked questions about infinitives
- What is a bare infinitive?
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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?
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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.
