An infinitive begins with the word to, followed by a simple verb form:
to run
to sleep
to eat.
An infinitive phrase contains an infinitive, along with other elements, such as modifiers, objects, and complements.
Examples of infinitive phrases
To kick a bin in anger
To push the car down the road
To lick a strawberry ice cream
To fall asleep in class
An infinitive phrase can function as an adverb, noun, or adjective.
Infinitive Phrase as Adverb
To relax, Fred watches basketball.
To build a nest, birds go to the branches in a tree.
Infinitive Phrase as Adjective
Sharks are magnificent creatures to behold in the sea.
Dogs are warm creatures to cuddle when it is cold.
Infinitive Phrase as Noun
To float underwater is amazing.
To parachute from a plane in the sky is exhilarating.
Bare Infinitives
Infinitive phrases usually begin with the word to, but when the phrase is missing to, it is called a bare infinitive. Compare the following lines:
Help me to lift the tire.
Help me lift the tire.
lift the tire is a bare infinitive phrase.
Notes
In most cases, use a comma to set off an introductory infinitive phrase:
To avoid a detention for failing to do her homework, Naomi quickly completed the graph while her teacher was taking the register.
Also use commas when a main clause is broken by an infinitive phrase:
That bright red lipstick, to be frank, does not go with the outfit you are wearing to the conference.
Infinitives can be split. A split infinitive contains words between the word to and the verb that follows it:
We need to seriously see that performance at the circus.
Splitting infinitives does not always yield an eloquent outcome. In such cases, you can move words around to close the infinitive:
We seriously need to see that performance at the circus.
Don’t confuse infinitive phrases with prepositional phrases that start with the word to. Infinitive phrases use to with a verb, while prepositional phrases use to with a pronoun or noun:
Prepositional phrase: I am going to my garden shed.