Infinitives – Definition, Examples, Overview
- Infinitives are the base form of a verb, often introduced by to.
- They can function as a noun, adjective, or adverb in a sentence.
- Infinitives do not change according to subject or tense.
- They are commonly used after certain verbs, adjectives, and nouns.
English infinitives are commonly divided into four main forms: simple, continuous, perfect, and perfect continuous, and they can also appear in the passive form.
What Are Infinitives?
An infinitive is the most basic form of a verb. In English, it is usually written as:
to + base verb
Examples:
- to read - I like to read before going to bed every night.
- to write - She wants to write a novel about her travels.
- to travel - We hope to travel to Japan next summer.
- to study - He needs to study for his math exam this weekend.
How to Form
The most common form is the to-infinitive: to + base verb.
English also uses the bare infinitive (or zero infinitive), which is just the base verb without to, especially after modal verbs, perception verbs, and verbs like let and make.
Examples:
- To-infinitive: to play, to speak, to write
- Bare infinitive: play, speak, write
Types of Infinitives
| Form | Structure | Example |
| Full infinitive | to + base verb | to write |
| Continuous infinitive | to be + verb-ing | to be writing |
| Perfect infinitive | to have + past participle | to have written |
| Perfect continuous infinitive | to have been + verb-ing | to have been writing |
Full Infinitive (with to)
Examples:
- to eat
- to learn
- to speak
Used after most verbs.
She decided to leave early.
Remember: the bare infinitive is used without "to" after modal verbs and certain verbs like make, let, see, hear, and feel.
Examples:
- You must study.
- Let him speak.
- I heard her sing.
Continuous, Perfect, and Perfect Continuous Infinitives
Continuous Infinitive
Structure: to be + verb-ing
- She seems to be writing a story.
- They appear to be studying for the exam.
Perfect Infinitive
Structure: to have + past participle
- She claims to have written the report already.
- I'm glad to have eaten before the meeting.
Perfect Continuous Infinitive
Structure: to have been + verb-ing
- He seems to have been working all night.
- They appear to have been studying for hours.
Functions of Infinitives
There are two main types of infinitives: full infinitives and bare infinitives. Let's discuss their functions in more detail.
Full Infinitives
Full infinitives (to + base verb) are used in several common ways in English.
1) To Show Purpose or Intention (Adverb)
Explains why something happens.
- Mom left to buy milk.
- I called to ask a question.
2) To Modify Nouns (Adjective)
Describes the purpose or characteristic of a noun.
- We need a hero to save us.
- She has something to say.
3) As the Subject of a Sentence (Noun)
Refers to an action in a general sense.
- To travel is my dream.
- To forgive takes strength.
4) After Adjectives
Adds context after an adjective.
- I'm happy to be here.
- This tool is easy to use.
5) With too and enough
Explains the result or reason.
- The bag is too heavy to carry.
- She is old enough to drive.
6) After Relative Words (what, how, where, when, who, whom)
Used in phrases, not direct questions.
- I don't know what to do.
- She explained how to solve it.
7) After Certain Verbs
Some verbs are commonly followed by full infinitives.
Common verbs: want, need, decide, hope, plan, agree, promise, try, forget, learn
Bare Infinitives
Bare infinitives use the base verb without "to." They appear in specific grammatical patterns.
1) After Modal Verbs
Common modals: can, could, may, might, must, shall, should, will, would
Example: She can drive now.
2) After Perception Verbs (object + verb)
Common verbs: see, hear, feel, watch, notice, observe
Structure: verb → object → bare infinitive
Example: I saw him cross the street.
3) After let, make, and help
These verbs are directly followed by a bare infinitive, often with an object in between.
Common verbs: let, make, help, do
Example: She made me apologize.
4) After the Relative Word why (suggestions)
Used in short suggestion questions.
Examples: Why wait any longer?
5) After Expressions with had better and would rather
These fixed expressions take a bare infinitive.
Common expressions: had better, would rather, would sooner
Example: You had better leave now.
6) After and / or to Avoid Repeating "to"
When two infinitives share the same to, the second verb drops it.
Example pattern: to try and help, to go or stay
Example: She wants to try and help.
Other Infinitive Forms - Split Infinitives
A split infinitive happens when a word (usually an adverb) comes between to and the base verb.
Structure: to + adverb + verb
- She decided to quickly finish the task.
- He tried to carefully explain the problem.
Passive Infinitives
A passive infinitive shows that the subject receives the action, not performs it.
Structure: to be + past participle
- She hopes to be chosen for the team.
- The work needs to be completed today.
Continuous Infinitives
A continuous infinitive shows an action that is in progress.
Structure: to be + verb-ing
- He seems to be working late.
- They appear to be waiting for us.
Forms of Infinitives in Sentences
An infinitive can modify a noun, acting as an adjective to describe the noun's purpose, function, or characteristic.
- We built a house to live in.
- The right thing to do isn't always clear.
An infinitive can modify a verb, adjective, or another adverb, explaining why, how, when, or to what extent something happens.
- She called to ask a question (modifies called).
- He paused to think carefully (modifies paused).
- I'm happy to help (modifies happy).
- They ran quickly to catch the bus (modifies ran).
Look for the infinitive answering why, how, when, or to what degree in relation to the main action.
An infinitive can act as the subject of a sentence, usually placed at the beginning.
- To learn a new language is challenging.
- To travel the world is her dream.
- To forgive someone can take time.
- To succeed requires patience and effort.
Tip: The subject infinitive is often moved to the end and replaced with it:
It is important to exercise daily.
A gerund is the -ing form of a verb (reading, jumping, exercising) and always functions as a noun.
An infinitive (to read, to jump, to exercise) can function as a noun, adjective, or adverb.
Examples:
- Correct: I'm thinking about going back to school.
- Incorrect: I'm thinking about to go back to school.
The word to can act as a preposition or as part of an infinitive.
- If to is followed by a noun, it is a preposition.
- We're going to the pool.
- She spoke to the manager.
- If to is followed by a base verb, it is an infinitive.
- We want to swim.
- He tried to explain.
Infinitive Phrases
An infinitive phrase includes an infinitive (to + verb) plus the words that complete its meaning, such as objects or modifiers.
- I went to watch the sunrise.
- The teacher asked the class to listen carefully.
She can paint beautiful pictures very quickly.