Costume is a noun that refers to a set of clothes worn by someone for a specific purpose, such as a play, Halloween, or a party. The word "costume" has many synonyms, like "attire," "disguise," "dress-up," "ensemble," "outfit," "garb," and "get-up." "Attire" refers to clothing in general, while "disguise" refers to clothing that conceals or changes the wearer's identity. "Dress-up" and "ensemble" are mostly used in the context of children playing or presenting a play or skit. "Garb" and "get-up" are both more old-fashioned terms used to describe clothing. Using synonyms can help avoid repetition in writing and make a piece more engaging.