Double-check vs. Double Check vs. Doublecheck
For the ordinary verb or noun meaning “check again,” major dictionaries use the hyphenated form “double-check.” An open “double check” can arise in other structures and has a specialized chess sense, so it should not be treated as a universal substitute; the closed “doublecheck” is not the general dictionary form used here.
For the general “check again” meaning, use the dictionary form “double-check”; treat “double check” according to its sentence or specialized context rather than as the default spelling.
Key details
Choose the right form
| Use | Preferred form | Why |
|---|---|---|
| Verb meaning check again | double-check | This is the ordinary dictionary headword for the check-again action. |
| Noun meaning a second check | double-check | The hyphenated form is also the ordinary noun form in the reviewed dictionaries. |
| Open wording in another structure or specialized sense | double check | Treat the open form according to that specific structure; it is not the default spelling of the ordinary check-again verb. |
| Closed spelling | doublecheck | Do not use as the general dictionary form in ordinary edited prose. |
Quick tests
Meaning-and-form test
Do you mean “check again” in ordinary prose?
If yes: Use “double-check” as the default verb or noun.
If no: If the words have a distinct grammatical or specialized use, evaluate that construction separately rather than closing the word automatically.
Caveat: The open form can occur in other structures, so the rule is about the ordinary check-again meaning rather than every possible sequence of “double” and “check.”
Examples
Please double-check the figures before we publish.
The ordinary check-again verb is hyphenated.
A quick double-check found the missing digit.
The ordinary noun is also hyphenated.
Please doublecheck the figures.
Better: Please double-check the figures.
The closed spelling is not the general dictionary form used by the reviewed sources.
Further guidance
Core difference
“Double-check” is the ordinary dictionary headword for checking again. The open wording can have a different structural or specialized use rather than being the default spelling of that verb.
Usage Boundary
Use the hyphenated form for the general check-again verb/noun unless a specific style or syntactic context clearly calls for something else; do not default to the closed “doublecheck”.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- double-check — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Hyphenated ordinary verb/noun headword meaning to check again
- double-check — Collins English Dictionary (opens in a new tab)Collins English Dictionary · Hyphenated general form and distinct open-form chess usage