ultimate guide to infinitive form

What Does the Infinitive Form Mean?

The infinitive form is the most basic form of a verb. It doesn’t have a tense, and it isn’t tied to any one subject in a sentence.

In the sentence He is going to go to the shop., "to go" is the infinitive. You can normally spot an infinitive because it has to at the start (though sometimes they don’t—more on that later).

If we change who is going to the shop, like this:

  • She is going to go to the shop.
  • They are going to go to the shop.

you can see that the infinitive, to go, doesn’t change.

what is the infinitive form

It’s the same with tense. Whether you’re writing in the past, present, or future tense, the infinitive stays the same.

Past: They wanted to go to the theatre.

Present: Do you want to go to the theatre?

Future: I am going to go to the theatre next Saturday.

This is because the infinitive is never the main verb in the sentence. In the examples above, the main verb phrases are "they wanted," "you want," "I am going."

As you can see, those phrases do change according to the tense and the subject. This is a good way to tell the difference between normal verbs and infinitives.

How Do You Write the Infinitive Form?

In the infinitive form, "to" is a part of the verb. To write the infinitive form, you’ll normally need this formula:

"to" + verb

(Again, sometimes you can get rid of the "to," but we’ll look at that later.)

What Is a Verb?

Need a quick refresher on verbs? No problem. A verb is a doing word. They denote an action or a state of being. Here are some verb examples:

  • Hear
  • See
  • Be
  • Do
  • Walk
  • Wear
  • Call
  • Write

It’s important to note that some of these words aren’t always verbs in every sentence—some can also be used as nouns. Check out our complete guide to verbs for more info.

Examples of Infinitive Forms

So, how do you turn those verbs into infinitives? Just add "to."

Here are 15 more examples of the infinitive form to help you learn how it works:

  • To be: I want to be the leader.
  • To do: I don’t know what to do.
  • To see: He went to see the doctor.
  • To hear: I have some news you might not want to hear.
  • To learn: She is trying to learn Spanish.
  • To take: I am going to take a vacation.
  • To have: They would like to have dinner with you.
  • To sleep: Did you manage to sleep well?
  • To care: I stayed there to care for her while she was sick.
  • To eat: Have you had enough to eat?
  • To promise: She wanted me to promise not to do it again.
  • To wear: I have nothing to wear.
  • To want: That is a strange thing to want.
  • To dance: Would you like to dance with me?
  • To read: She loves to read thriller novels.

As you can see, the infinitive stays the same regardless of tense or sentence subject.

The Full Infinitive and the Bare Infinitive

Most of the time, you won’t need to be able to name the exact type of infinitive you’re using, and the definition above will be enough to get you through.

But just in case you need to know what the full infinitive and the bare infinitive are, we’ve got you covered.

So far, we have been looking at the full infinitive. The full infinitive is any infinitive with "to" at the start (to eat, to dream, to dance, etc.).

You may have also heard of the bare infinitive. All this means is that we take away the "to" (eat, dream, dance).

full infinitive vs. bare infinitive

How Does the Bare Infinitive Work in a Sentence?

She could play the piano beautifully.

In this sentence, the bare infinitive is "play." It is called the bare infinitive because there is no "to" before it.

It would be wrong to write She could to play the piano beautifully.

If you’re unsure whether to use "to" with an infinitive, check with ProWritingAid. It’ll highlight when you’ve used an infinitive incorrectly and show you how to fix it:

incorrect infinitive highlighted in ProWritingAid

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Here are some examples of bare infinitives in a sentence. They’re in bold to help you spot them.

  • Mom made me bring my sister.
  • I’d rather be on my own.
  • You had better take a coat with you.
  • He should know better than that.
  • I heard them sing at a festival.
  • You must get up for school.
  • Why wait until next year?

Can I Use an Infinitive as a Noun, Adjective, or Adverb?

What a specific question! Yes, you can use an infinitive as a noun, adjective, or an adverb. In each case, the infinitive will play a different role in the sentence:

  • Noun: a word that denotes a thing, place, person, or idea
  • Adjective: a word that describes a noun
  • Adverb: a word that modifies (changes the meaning of) a verb

What Are Examples of an Infinitive Used as a Noun?

When you use an infinitive as a noun, you use it to denote an idea or thing, like this:

  • I want to know.

To know stands in for the thing that I want in this sentence (knowledge). This infinitive therefore acts as a noun.

infinitive as a noun

Here are some more examples:

  • After a long day, Janelle likes to soak in a hot bath.
  • I love to dance.
  • She refuses to cater to his every whim.
  • I need to learn my words.
  • To visit the Grand Canyon is his life-long dream.
  • To know him to to love him.

As in the examples above, the noun infinitive phrase can go at the end or the beginning of the sentence, though it’s more common to see it at the end.

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How Do I Use the Infinitive as an Adjective?

An adjective describes a noun. So when you use an infinitive to describe a noun, you’re using it as an adjective.

  • Jennifer’s first attempt to win the gold medal failed.

Here, the noun is "attempt." The phrase "to win the gold medal" describes the noun—the "attempt."

  • He used computer software to build the game.
  • She wore her mom’s necklace to give her good luck.
  • I am happy to be here.
  • It is good of you to think of me.
  • The puppy is naughty to destroy the sofa.

What Are Examples of the Infinitive Used as an Adverb?

When you use the infinitive to modify (or change the meaning of) a verb, you’re using it as an adverb.

  • She ran to catch the bus in time.
  • He sent a letter to make a complaint.
  • They were studying to prepare for the exam.
  • To keep you safe, we’re continuing to wear face coverings.
  • Jessica went to New York to study acting.

using an infinitive as an adverb

As you can see, the infinitive phrase can go at the beginning or end of the sentence:

  • To keep you safe, we’re continuing to wear face coverings.
  • We’re continuing to wear face coverings to keep you safe.

What Does the Infinitive Phrase Mean?

You’ve already seen some infinitive phrases in the examples above.

Here are three of those examples with the infinitive phrases highlighted:

  • After a long day, Janelle likes to soak in a hot bath.
  • They were studying to prepare for the exam.
  • She wore her mom’s necklace to give her good luck.

As we’ve said, an infinitive phrase can go at the beginning or end of the sentence, but the end is more common. A famous exception is the line "To be or not to be, that is the question" from Hamlet.

using an infinitive as a noun

You can use infinitives to make lots of different kinds of statements. Let’s look at a few.

To Explain a Description of Something

Infinitives are used after an adjective to expand an idea. For example:

  • The puppy is naughty to destroy the sofa.

Here, we are told not only that the puppy is naughty (adjective) but that it was the action of destroying the sofa that made him naughty. The infinitive to destroy expands on the adjective, naughty.

Examples of infinitives being used to explain adjectives:

  • It is good of you to think of me.
  • I am happy to be here.
  • It is important for students to be patient in the laboratory.

infinitive after an adjective

To Explain Why You Like/Dislike Something

If you use an infinitive with the words "too" or "enough," you can express the reasoning behind satisfaction or dissatisfaction.

  • There’s too much sugar to fit in this bowl.

The bowl is no good because it isn’t big enough to fit all the sugar.

  • I had too many books to carry.
  • This soup is too hot to eat.
  • Jeff was too tired to work.
  • He arrived too late to hear the opening chorus.
  • I’ve had enough food to eat.
  • She’s old enough to decide for herself.
  • There isn’t enough snow to ski down the slope.

To Make a Comment or Judgment About Something

Use infinitives to make a comment or judgment about a noun in a sentence.

For example:

  • Climbing the beach cliff is a dangerous way to behave.

Here, the infinitive tells us that the judgement is being made specifically about behaviour.

More examples of making a judgement with an infinitive:

  • Your comment was a rude thing to say.
  • This is the right thing to do.
  • Those were the wrong formulas to use.
  • Jack is the best candidate to hire.

To Ask a Question

The verbs ask, decide, explain, forget, know, show, tell, and understand can be followed by a question word such as where, how, what, who, and when + the infinitive to form a question.

It’s easier when you see some examples:

  • She asked me how to use the new computer.
  • Do you understand what to do?
  • Tell me when to press the button.
  • I’m not sure I know who to call.

using infinitives to ask a question

Now you know what the infinitive form is, you can begin to add infinitive phrases to your sentences.

See what we did there?

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Common Questions about Infinitives

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