Lookout vs. Look Out
“Lookout” is a noun for a person who watches for danger or a place used for watching. “Look out” is a two-word phrasal verb meaning to watch carefully or be careful, and it is also used as a warning.
Use “lookout” for the noun and “look out” for the phrasal verb or warning.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| noun naming a watch, warning point, or person keeping watch | lookout | Use the closed noun. |
| phrasal verb or warning | look out | Use the two-word verb. |
Quick tests
Meaning / construction test
Is the expression functioning as a noun?
If yes: Use “lookout.”
If no: Use “look out” for the verb or warning.
Examples
The lookout spotted smoke on the ridge.
The closed form is a noun.
Look out for cyclists at the junction.
The two-word form is a phrasal verb.
We stopped at a scenic lookout.
The closed form names a place or point for viewing.
Further guidance
Core difference
Use “look out” when the expression functions as a verb; use the documented noun form for the person, thing, event, result, or modifier.
Fast Test
If tense or inflection works naturally—such as a past or -ing form—you are using the verb and should keep “look out” as separate words.
Variant Boundary
Cambridge separates the closed noun “lookout” from the two-word phrasal verb “look 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.
- LOOKOUT — English meaning (opens in a new tab)Cambridge Dictionary · Closed noun “lookout” for a watcher/place and related noun uses
- LOOK OUT — English meaning (opens in a new tab)Cambridge Dictionary · Two-word phrasal verb “look out” and warning expression