Mix-up vs. Mix Up
Cambridge distinguishes the two-word phrasal verb “mix up” from the hyphenated noun “mix-up.” The candidate spelling “mixup” is therefore normalized to the dictionary-backed noun form rather than treated as the default closed noun.
Use “mix up” for the phrasal verb and “mix-up” for the noun meaning a mistake or confused situation.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| mistake, confusion, or confused situation as a noun | mix-up | Use the hyphenated dictionary noun. |
| combine, confuse, or mistake one thing/person for another as a verb | mix up | Use the two-word phrasal verb. |
| closed noun “mixup” as the default spelling | not the reviewed dictionary headword | Prefer the documented “mix-up” unless another governing style/source establishes the closed form. |
Quick tests
Meaning / construction test
Is the expression functioning as the verb?
If yes: Use “mix up.”
If no: For the noun, use the documented hyphenated form “mix-up.”
Caveat: This three-form comparison is not purely binary: the reviewed Cambridge entry supports “mix-up” as the noun and “mix up” as the verb, while the closed “mixup” is not the noun form established by that source.
Examples
There was a mix-up with the booking.
The hyphenated form is the noun naming the confusion.
Do not mix up the two account numbers.
The two-word form is the phrasal verb.
The labels were mixed up during packing.
The inflected phrasal verb remains two words.
Further guidance
Core difference
Use “mix up” as the phrasal verb and “mix-up” as the noun for a mistake or confused situation.
Fast Test
If the expression is an action that can become “mixed up” or “mixing up,” use two words. If it names the resulting mistake/confusion, use the hyphenated noun.
Usage Boundary
Do not close the noun as “mixup” merely because similar noun/verb pairs sometimes become closed compounds; Cambridge gives “mix-up.”
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.
- Mix up / mix-up — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct dictionary evidence distinguishing phrasal verb “mix up” from hyphenated noun “mix-up.”