An infinitive consists of the word “to” plus a verb ("to be," "to have," "to run," "to buy" etc); it may be used as a noun, adjective or adverb. An infinitive phrase is a group of words consisting of an infinitive, a modifier or the use of pronouns, direct objects, indirect objects or complements of action or state expressed in the infinitive.
- Don’t confuse an infinitive with a prepositional phrase beginning with “to.” Prepositional phrases consist of “to” plus a noun, pronoun or any modifiers.
Infinitives include: to become, to enter, to draw, etc.
Prepositional phrases include: to him, to this address, to the mountains, to my house, etc.
- An infinitive phrase uses an infinitive plus a modifier, object, complement or actor. There can be more than one of these and they may not all be present in the phrase.
- Infinitive phrases only require a comma when used as an adverb at the beginning of the sentence.
- “To wait seemed foolish when decisive action was needed.” –subject
- “Everyone wanted to go.” –direct object
Does your infinitive phrase have additional words between “to” and the verb? If so, it’s a split infinitive. In some cases, it’s acceptable (“To boldy go where no man has gone before”), but it generally should be avoided in formal papers.
- Informal papers: I needed to quickly gather my school supplies.
- Formal Papers: I needed to gather my school supplies quickly.