Adverbial Infinitive: Definition, Usage, and Examples in English Grammar

Introduction

An adverbial infinitive is a grammatical construction where an infinitive verb (to + base form of the verb) functions as an adverb, modifying a verb, adjective, or another adverb in a sentence. Unlike regular adverbs, which are single words (e.g., quickly, very), adverbial infinitives provide additional information about purpose, reason, result, or condition.

This article explores the structure, types, and correct usage of adverbial infinitives, along with practical examples to enhance your understanding.

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What Is an Adverbial Infinitive?

An adverbial infinitive consists of:

• "To" + base verb (e.g., to run, to study, to improve)

• It answers questions like:

  • Why? (Purpose)

  • How? (Manner)

  • Under what condition?

Example:

• Main Clause: She woke up early.

• Adverbial Infinitive: to catch the bus.

• Complete Sentence: She woke up early to catch the bus.

Here, the infinitive "to catch" explains the purpose of waking up early.

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Types of Adverbial Infinitives

1. Infinitive of Purpose

Indicates why an action is performed.

Examples:

• He studies hard to pass the exam.

• They saved money to buy a new house.

2. Infinitive of Result

Shows the outcome of an action.

Examples:

• She was too tired to continue working.

• The box was heavy enough to require two people.

3. Infinitive of Condition

Expresses a hypothetical situation (often with "were to" or "should").

Examples:

• Were he to apologize, she would forgive him.

• Should you need help, call me immediately.

4. Infinitive of Manner

Describes how an action is done (less common).

Example:

• She gestured to indicate her agreement.

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How to Identify an Adverbial Infinitive

Ask:

1. Does it modify a verb, adjective, or adverb?

2. Does it answer "why," "how," or "under what condition"?

If yes, it’s likely an adverbial infinitive.

Comparison with Other Infinitives

• Noun Infinitive: Acts as a subject/object (To err is human).

• Adjective Infinitive: Modifies a noun (She has a book to read).

• Adverbial Infinitive: Modifies a verb/adjective (She ran to win).

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Common Mistakes & How to Avoid Them

1. Splitting Infinitives Unnecessarily

• ❌ She wanted to quickly finish her work.

• ✅ She wanted to finish her work quickly. (More natural)

(Note: Split infinitives are sometimes acceptable for emphasis, e.g., "to boldly go".)

2. Misplacing the Infinitive

• ❌ He bought a bike to ride his son. (Illogical)

• ✅ He bought a bike for his son to ride. (Correct)

3. Confusing with Prepositional Phrases

• ❌ She went to the store for buying groceries. (Incorrect)

• ✅ She went to the store to buy groceries. (Correct)

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Punctuation Rules

• No comma is needed when the infinitive follows the main clause.

  • She exercises daily to stay healthy.

• Use a comma if the infinitive starts the sentence for clarity.

  • To improve his skills, he practiced daily.

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Conclusion

Adverbial infinitives add depth to sentences by explaining purpose, result, or condition. Mastering their use improves writing clarity and sophistication.

Key Takeaways:

✔ Functions as an adverb (modifies verbs/adjectives).
✔ Common types: Purpose, result, condition, manner.
✔ Avoid errors like misplaced or split infinitives.

Practice Tip: Try converting adverbial clauses into infinitives for conciseness:

• Because she wanted to succeed, she worked hard. → She worked hard to succeed.