Blackout vs. Black Out
“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.
Use “blackout” as the noun for a loss of power/light, a reporting restriction, or a brief loss of consciousness. Use “black out” as the verb for becoming unconscious or making something dark or unreadable.
Key details
Choose the right form
| If you mean / need | Use | Why |
|---|---|---|
| an outage, information restriction, or brief unconscious period as a noun | blackout | Cambridge records the closed noun. |
| the action of becoming unconscious or obscuring/darkening something | black out | Cambridge records the phrasal verb as two words. |
Further guidance
Core difference
Use the documented noun or modifier form when naming a thing, result, event, 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 verb form is usually the relevant choice.
Variant Boundary
Cambridge distinguishes the closed noun “blackout” from the two-word phrasal verb “black out.”
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.
- Blackout — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Closed noun “blackout” for loss of power/light, suppressed information, or brief unconsciousness
- Black out — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Two-word phrasal verb “black out” for becoming unconscious or obscuring/darkening something