What Is an Infinitive Phrase? | Definition & Examples

An infinitive phrase is formed when an infinitive is followed by modifiers (e.g., adverbs) or complements (e.g., direct objects). Infinitive phrases can be used in the same ways as infinitives: as nouns, adverbs, and adjectives.

What is an infinitive phrase?

An infinitive in English is a verb form that is the same as the base or dictionary form. A full infinitive is preceded by “to” (e.g., “to eat,” “to read”), while a bare infinitive is not (e.g., “eat,” “read”). Infinitives can act as nouns, adverbs, and adjectives.

An infinitive can be followed by direct objects, indirect objects, or modifiers (e.g., adverbs). This group of words is known as an infinitive phrase. Both full infinitives and bare infinitives can form infinitive phrases, but full infinitives are more common.

Infinitive phrases can be used in the same ways as infinitives.

Using an infinitive phrase as a noun

Infinitive phrases can act as nouns when they are used as the direct object of the main verb, the subject of the sentence, or a subject complement. Subject complements follow linking verbs to describe, define, or identify the subject.

Using an infinitive phrase as an adjective

When an infinitive phrase modifies a noun, it behaves as an adjective describing the noun. For example, it might be describing its purpose or attributes.

Using an infinitive phrase as an adverb

Infinitive phrases can function as adverbs modifying a verb.

Adverb infinitive phrases won’t necessarily directly follow the verb they’re modifying. Ask these questions to determine whether an infinitive phrase is functioning as an adverb:

• Does it explain why an action occurred or is occurring?
• Can you replace the “to” in the infinitive with “in order to” without altering the meaning?

If the answer is “yes,” it’s an adverbial infinitive phrase modifying a verb.

Infinitive phrases vs prepositional phrases

A prepositional phrase consists of a preposition (e.g., “in,” “with,” “of”) followed by a noun or pronoun and any modifiers. Because “to” is a preposition, it can form part of a prepositional phrase.

To determine whether a phrase beginning with “to” is an infinitive or a prepositional phrase, look at what follows it.

“To” in a full infinitive is always followed by a verb, while “to” in a prepositional phrase is always followed by a noun or a pronoun.

Split infinitive phrases

A split infinitive occurs when words (usually adverbs) come between “to” and the verb in a full infinitive (e.g., “to slowly speak”). Split infinitives have traditionally been seen as incorrect or “bad grammar” because in Latin, infinitives are one word and can’t be split.

It’s sometimes unnecessary to split an infinitive. However, if you can rephrase a sentence without changing the meaning or emphasis, it can be the best choice to do so, especially in formal contexts.

However, split infinitives can also be the clearest, most logical, or most correct way to phrase a sentence, and they don’t need to be avoided entirely.

Frequently asked questions about infinitive phrases

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.

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”).