C1 Grammar Style

Split Infinitives

A split infinitive places a word — usually an adverb — between to and the verb: to boldly go. Despite an old "rule" against it, the split infinitive is grammatically fine and often the clearest choice.

The English infinitive is the base verb introduced by to: to go, to understand, to decide. A split infinitive happens when a word, most often an adverb, is inserted between to and the verb, as in to really understand or the famous to boldly go where no one has gone before. For over a century, some teachers insisted this was an error, but modern grammarians and every major style guide agree the split infinitive is correct English.

The old taboo came from nineteenth-century writers who tried to make English behave like Latin, where the infinitive is a single word that cannot be split. English infinitives are two words, so there is nothing to break. The real question is not "is it allowed?" but "where does the adverb read most clearly?"

Where the Adverb Can Go

An adverb modifying an infinitive can usually sit in three positions. Each can be correct, but they differ in clarity and emphasis.

Position Example Note
Split (between to and verb) I want to really learn it. Often clearest; emphasises the adverb
Before to I really want to learn it. Changes which verb the adverb modifies
After the verb I want to learn it really. Can sound awkward or ambiguous

When Splitting Improves Clarity

Sometimes refusing to split creates ambiguity or unnatural rhythm. The split is the best option when moving the adverb would change the meaning or attach it to the wrong word.

The clarity test: try the sentence with the adverb in each position. Choose the one that is unambiguous and reads smoothly. If only the split version is clear, split it without hesitation — clarity always beats an outdated rule.

When to Avoid Splitting

In very formal writing, or where a long phrase would awkwardly separate to from its verb, it is better to move the adverb.

Splitting With Negatives and Multiple Words

You can split with not and short phrases, but keep the insertion brief:

Common Mistakes

Practice Exercises

Grammar Quiz

Decide which adverb position reads most clearly.

Cloze Dropdown

Choose where to place the adverb in each sentence.

Complete the Sentence

Add an adverb to an infinitive without losing clarity.

Matching Pairs

Match sentences with their clearest adverb position.

Unjumble

Reorder words into a clear infinitive phrase.

Flash Cards

Drill split vs unsplit infinitive examples.

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Explore related grammar topics:

All Grammar Topics Gerunds & Infinitives Adverbs Word Order Dangling Modifiers

Frequently Asked Questions

What is a split infinitive?
A split infinitive is an infinitive (to + verb) with a word, usually an adverb, placed between the two parts: to boldly go, to quickly finish. The adverb modifies the verb but sits inside the infinitive rather than before or after it.
Is it wrong to split an infinitive?
No. Splitting an infinitive is grammatically correct, and every major modern style guide accepts it. The old ban came from trying to copy Latin, where infinitives are single words. In English the infinitive is two words, so there is nothing to break.
When should you split an infinitive?
Split when it is the clearest and most natural option, especially when moving the adverb would create ambiguity or attach it to the wrong verb: She decided to gradually reduce her hours. Clarity is the deciding factor, not the outdated rule.
Where did the rule against split infinitives come from?
It arose in the nineteenth century from grammarians who believed English should follow Latin. Because a Latin infinitive is one word that cannot be divided, they wrongly argued the English two-word infinitive should not be split either. Linguists have since rejected this reasoning.
When should you avoid splitting an infinitive?
Avoid it when a long phrase would separate to from its verb, harming readability, or in very formal or legal writing where some readers still object. If the adverb can move without losing clarity, the unsplit version may simply read more smoothly.
Can moving the adverb change the meaning?
Yes. She decided to gradually reduce her hours means the reduction is gradual, while She gradually decided to reduce her hours means the deciding was gradual. Adverb position controls which verb is modified, so choose the position that gives the meaning you intend.
What is the most famous split infinitive?
The best-known example is to boldly go where no man has gone before from Star Trek. Rewriting it as to go boldly weakens the rhythm and emphasis, which is exactly why the split version became iconic.
Can you split an infinitive with not?
Yes. He promised to never lie again is a split infinitive with not's cousin never, and it is perfectly acceptable in modern English. The more conservative alternative, He promised never to lie again, is also fine.
Can you split an infinitive with more than one word?
You can, but keep it short: We aim to fully and fairly assess each case still reads well. A long insertion, such as to, after careful consideration, decide, separates to from its verb too far and should be reworded.
Do split infinitives matter in exams like IELTS?
Examiners assess clarity and correctness, and split infinitives are correct, so they will not be penalised. Focus on writing unambiguous, natural sentences. Forcing an awkward unsplit version to avoid a non-existent error is more likely to lower your score than the split itself.