“Write-up” is a hyphenated noun for a report or article. “Write up” is a two-word phrasal verb used for putting something into complete written form and for related reporting senses.
ReviewedEvidence1 sourceSectionEnglish Usage
Quick answer
Use “write-up” for the noun and “write up” for the phrasal verb.
Key details
Confusion Familyword-boundary
Noun Variant ScopeCambridge presents “write-up” as the noun and “write up” as the phrasal verb.
Rule Familyorthographic-boundary
Termswrite-up, write up
Choose the right form
Decision table for Write-up vs. Write Up
If you mean / need
Use
Why
a report, review, or article
write-up
The noun is hyphenated.
the action of preparing or recording something in writing
write up
The phrasal verb is written as two words.
Further guidance
Core difference
Use the noun or modifier form documented by the dictionaries when naming a thing, event, result, or concept; use the spaced form when the words function as a verb.
Fast Test
If the expression can take ordinary verb tense or inflection in the sentence, the spaced phrasal-verb form is usually the relevant form.
Variant Boundary
Cambridge presents “write-up” as the noun and “write up” as the phrasal verb.
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.
Standard English writes “a lot” as two words for a large amount, number, frequency, or degree. “Alot” is a common misspelling in this sense; it should not be confused with the separate verb “allot.”
“Blackout” is the closed noun, while “black out” is the two-word phrasal verb. The verb can describe losing consciousness or obscuring/darkening something; the noun names the resulting event or state.
“Blowout” is a closed noun for several events or results, and Cambridge also records “blow-out” as a noun variant. “Blow out” is the two-word phrasal verb, including the sense of extinguishing a flame.
“Breakout” is a closed noun for an escape and an adjective in several established senses. Cambridge also documents “break-out” in modifier use. “Break out” is the two-word phrasal verb for meanings such as beginning suddenly or escaping.
“Breakthrough” is a closed noun for an important discovery or advance and can also modify a following noun. “Break through” is the two-word phrasal verb for forcing or moving through a barrier or threshold.
“Build up” is the two-word phrasal verb. For the noun, Cambridge records hyphenated “build-up,” while its American dictionary also records closed “buildup.” The noun spelling therefore has a documented regional/style variant rather than one universal form.
