A split infinitive occurs when an adverb or other modifier is placed between the word to and the base verb: to boldly go, to really understand, to carefully consider. For centuries, schoolteachers warned students never to do this. But where did this rule come from, and is it valid? The prohibition against split infinitives was invented by 19th-century grammarians who modelled English grammar on Latin. In Latin, infinitives are single words (amare = to love) and literally cannot be split. These grammarians applied the same logic to English, but English is not Latin, and the “rule” was never based on actual English usage. Today, every major modern authority — the Oxford English Dictionary, Cambridge Grammar, Chicago Manual of Style, and Fowler’s Modern English Usage — accepts split infinitives. The real question is not “Is it wrong?” but “Is it the best choice here?” Sometimes a split infinitive is the clearest, most natural option; other times, avoiding it produces better prose.
Formation / Rules
| Version | Example | Verdict |
|---|---|---|
| Split infinitive | to boldly go | Accepted in modern English |
| Adverb after infinitive | to go boldly | Correct; different emphasis |
| Adverb before ‘to’ | boldly to go | Formal/archaic; can feel stilted |
| Split causes ambiguity — avoid | to further cement / to cement further | “to further cement” may be unclear; prefer “to cement further” |
| Split changes meaning — keep split | to really help vs really to help | Split version emphasises degree of help |
Examples
- She wanted to quietly leave the room. (split; natural and clear)
- He tried to better understand the problem. (split; idiomatic)
- The aim is to further develop the project. (split; widely used in business)
- We need to carefully consider all options. (split; the adverb modifies the action precisely)
- “To boldly go where no man has gone before.” (famous split; now iconic)
- She managed to nearly double her salary. (split; avoids ambiguity)
- The policy aims to gradually reduce emissions. (split; natural word order)
- He tried to avoid to completely disrupt the schedule. (split; clear meaning)
Common Mistakes
| Situation | Awkward (no split) | Better (with split) |
|---|---|---|
| Meaning changes if moved | really to help (formal/archaic) | to really help (emphasises degree) |
| Adverb belongs with verb | to double nearly her salary | to nearly double her salary |
| Multiple adverbs become clunky | slowly and carefully to approach | to slowly and carefully approach (or rewrite) |
| Ambiguity without split | We want to really help. vs We really want to help. | Keep split for nuance: to really help. |
Practise
Grammar Quiz
Decide whether to split or not to split the infinitive.
Cloze Dropdown
Place the adverb in the best position in the infinitive phrase.
Complete the Sentence
Rewrite sentences to improve or justify split infinitive use.
Practice What You’ve Learned
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Frequently Asked Questions
What is a split infinitive?
A split infinitive occurs when an adverb or other word is placed between ‘to’ and the base verb: ‘to boldly go’, ‘to really understand’, ‘to carefully consider’. The adverb splits the two parts of the infinitive.
Are split infinitives grammatically wrong?
No. Split infinitives are not grammatically wrong in English. The rule against them was invented in the 19th century by grammarians who modelled English on Latin. Modern style guides (Oxford, Cambridge, Chicago) consider split infinitives acceptable.
When should I avoid split infinitives?
Avoid split infinitives in very formal or traditional contexts (legal documents, conservative style guides). Also avoid them when the split creates awkwardness. When avoidance creates ambiguity or awkwardness, the split is preferable.
When is it better to split an infinitive?
Split the infinitive when not doing so creates ambiguity or changes meaning. ‘We want to really help’ has a different emphasis from ‘We really want to help’ or ‘We want to help really’. Sometimes only the split version conveys the intended nuance precisely.
What is the most famous split infinitive in English?
“To boldly go where no man has gone before” from Star Trek is the most famous split infinitive in popular culture. Moving ‘boldly’ changes the sentence: ‘to go boldly’ or ‘boldly to go’ both feel less natural and rhythmically different from the original.
Why was the split infinitive once considered wrong?
In Latin, infinitives are single words (amare = to love) and cannot be split. 19th-century grammarians tried to apply Latin rules to English, declaring it incorrect to split the English infinitive. This was a prescriptive rule based on a false analogy with Latin, not on how English actually works.
Do Oxford and Cambridge style guides allow split infinitives?
Yes. The Oxford English Dictionary and Cambridge Grammar of the English Language both accept split infinitives. The Oxford style guide states that avoiding a split infinitive ‘can cause ambiguity or stiltedness.’ Fowler’s Modern English Usage also revised its original opposition.
Can only adverbs split infinitives?
Typically yes. The most common split infinitives insert an adverb between ‘to’ and the verb: to quietly leave, to further develop, to better understand. Other modifiers can also appear there but are rarer and usually more awkward in practice.
How do I decide whether to split or not to split?
Ask: (1) Does the split infinitive create ambiguity? (2) Does avoiding it create awkwardness or change meaning? (3) What does my audience expect? For most modern contexts, split infinitives are fine. For traditional academic or legal writing, keep the infinitive together.
Are split infinitives tested in IELTS or Cambridge exams?
Split infinitives are not specifically penalised in IELTS or Cambridge exams since they are accepted in modern standard English. Examiners focus on accuracy of verb forms, tense, agreement, and sentence structure rather than this stylistic preference.