Sentence examples for a costume from inspiring English sources

The phrase "a costume" is correct and usable in written English.
It can be used when referring to an outfit worn for a particular occasion, such as a party, performance, or celebration, often associated with dressing up as a character or theme.
Example: "For Halloween, I decided to wear a costume that resembled my favorite superhero."
Alternatives: "an outfit" or "a disguise".