What is an infinitive?

An infinitive is formed from a verb but doesn't act as a verb.

It acts as a noun, adjective, or adverb, and it is actually made up of two words: to + verb.

These two words act together as a noun, adjective, or adverb.

I love to swim(noun)

The person to call is Jeff. (adjective)

I can't wait to see! (adverb)

What is an infinitive? I'll teach you!

Kittens want to play. (noun)

Words that are formed from verbs but don't act as verbs are called verbals. There are two other types of verbals: gerunds and participles.

Where's the To?

Sometimes, identifying these guys in sentences can be tricky because the word to is omitted. That's not very nice, is it?

When this happens, we call them bare infinitives.

They usually occur after certain verbs like feel, hear, help, let, make, see, and watch.

Here are some examples. I'll underline the special verbs so that you can see where they are. The bare infinitives are in bold.

They watched the ship sail.

heard the doorbell ring.

When Margo slammed the door, she made the painting fall.

Infinitive Phrases

I love to swim in lakes.

These are made up of an infinitive and the words that modify and complement it.

Edward loves to run. Edward loves to run marathons.
Esme used the binoculars to see. Esme used the binoculars to see her favorite band.
Jack waited to eat. Jack waited to eat the cupcake.

Modifiers & Complements

Do you remember what these act as? NOUNSADJECTIVES, and ADVERBS right?

Let's look at one of the examples from above.

I love to swim in lakes.

The whole phrase together is acting as a noun (the direct object of love), but you may have noticed that in lakes is an adverbial prepositional phrase. It is telling us where you like to swim.

Does that means that an adverb (in lakes) is modifying a noun (to swim)?

Yes! Since these guys are formed from verbs, they maintain some attributes of verbs even though they act as nouns, adjectives, and adverbs.

Even if it is acting as a noun, its "verbness" allows it to take adverbial modifiers just like other verbs. (But it can still take adjectival modifiers just like other nouns.)

They can even take complements (like direct objects), just like verbs can.

In a Sentence
Acting As...
Its Complement/Modifier
Edward loves to run marathons. Direct Object Marathons is the direct object of run.
Esme used the binoculars to see her favorite band. Direct Object Band is the direct object of see, and her and favorite are adjectives (possessive pronouns) modifying band.

Basic Sentence Diagramming

Place the word to on an angled line, and write the verb on a horizontal line coming off the angled line.

With a forked line, connect this to the rest of the sentence wherever it should go. (These guys can be nouns, adjectives, or adverbs.)

I want to win.

Infinitive Sentence Diagram

After that, you can add any complements or modifiers.

I want to win the game.

Infinitive Phrase Sentence Diagram

Other Helpful Resources

The Beginner's Guide to Grammar gives you a fun and visual way to get started with grammar and sentence diagramming. Yay!

Finished? Go Back to Phrases.