Infinitive Verbs

1) Infinitive Verbs

Definition & Basic Structure.

An infinitive is the most basic form of a verb, typically preceded by the word “to.” Although it is formed from a verb, an infinitive does not function as the main action of a sentence (the finite verb); instead, it acts as a noun, adjective, or adverb.

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Common Form
to + verb (e.g., to eat, to sleep, to study)

2) The Functions of Infinitives

Versatile positions in a sentence.

Function Example Notes
As a Noun (Subject) To travel is her greatest dream. Acts as the subject of the sentence.
As a Noun (Direct Object) He decided to stay. Receives the action of “decided”.
As an Adjective I have some work to finish. Modifies the noun “work”.
As an Adverb She exercised to improve her health. Explains why she exercised.

3) The Three Types of Infinitives

Variations in structure.

Type Structure Example
Full Infinitive to + base verb I want to learn French.
Bare Infinitive base verb (no “to”) She let him go.
Split Infinitive to + adverb + verb They decided to quickly finish the task.

4) Key Usage Rules

Grammatical structures and specific patterns.

A) The Bare Infinitive

We omit the “to” in specific grammatical structures:

After Modal Auxiliaries

Can, could, may, might, shall, should, will, would, must.

  • Correct: I can swim.
  • Incorrect: I can to swim.
After Verbs of Perception

See, hear, feel, watch.

  • Correct: I saw him cross the street.
After “Let,” “Make,” and “Help”
  • Correct: Don’t make me laugh.
  • Note: “Help” can use both: Help me clean OR Help me to clean.

B) Negative and Comparison Rules

Negative Infinitive

Place not immediately before the “to”.

  • Positive: She told me to stay.
  • Negative: She told me not to stay.
The “Too” and “Enough” Rule
  • Too + Adj + Infinitive: It is too cold to swim.
  • Adj + Enough + Infinitive: He is brave enough to try.

C) After Specific Verbs

Certain verbs are almost always followed by an infinitive rather than a gerund (-ing):

  • Agree, decide, hope, plan, refuse, want, promise.
  • Example: “We plan to visit Japan next year.”

5) Infinitives vs. Gerunds

Contextual meaning changes.

While both can act as nouns, the choice depends on the preceding verb. Some verbs change meaning depending on which you use:

Stop + Infinitive

You paused your current activity in order to do something else.

  • Stop to eat.
Stop + Gerund

You finished the actual act of the verb.

  • Stop eating.