infinitive, infinitive phrase

An infinitive is a type of verbal—a verb form that looks like a verb but does not act as the verb in a sentence.

An infinitive is the basic form of a verb, usually with to in front of it: to go, to stay, to be. Infinitives act as nouns, adjectives or adverbs:

• Larissa wants to leave. [noun, object of verb wants]
• I can show you the way to go. [adjective modifying noun way]
• To exit, please turn to your left. [adverb modifying verb turn]

An infinitive phrase is an infinitive with attached words. Because an infinitive is formed from a verb, it retains some of the properties of a verb, so it can take an object:

• Larissa wants to leave the concert. [infinitive to leave + object the concert]

Like a verb, an infinitive can also be modified by an adverb or a prepositional phrase:

• To exit quickly, please turn to your left. [infinitive to exit + adverb quickly]
• I can show you the way to reach the exit from here. [infinitive to reach + object the exit + prepositional phrase from here]

In the above examples, to leave the concert, to exit quickly and to reach the exit from here are all infinitive phrases.

Infinitive phrases may have their own subjects. The subject of an infinitive phrase is in the object form:

• Yuri helped him to count the money.
• Alison allowed me to drive her Porsche.

Sometimes the word to is left out:

• Yuri helped him count the money.
• Alison let me drive her Porsche.

An infinitive without to is called a bare infinitive.

Other infinitive forms

We can change the form of the infinitive to show different times:

• An avid skier, Roberta appeared to be praying for snow. [Ongoing action at the same time: She was praying when the speaker saw her.]
• Marty seems to have forgotten his wallet. [Completed action at an earlier time: He forgot it before this comment was made.]
• The tenant is thought to have been cooking at the time of the fire. [Ongoing action at an earlier time: The tenant was in the process of cooking when the fire broke out, as the investigators now believe.]

Infinitives can also be used in the passive voice:

• The roof needs to be repaired as soon as possible.
• This man claims to have been abducted by aliens.