A costume is clothing worn to make you look like someone or something else. On Halloween, kids might wear costumes to transform into superheroes, pirates, or their favorite book characters. Actors wear costumes in plays and movies to become the people they're portraying: a costume helps an actor playing Abraham Lincoln look like the real president, complete with a black suit and stovepipe hat.

Costumes create a complete illusion and help you imagine being someone else. When you put on an astronaut costume, the white suit helps you imagine floating in space. When an actor steps into the costume of a medieval knight, the armor and chainmail help them feel and move like someone from centuries ago.

The word can also describe the typical clothing of a particular time or place, like traditional Japanese clothing or colonial American clothing. Museums often display historical costumes to show how people dressed long ago. Costume designers are professionals who create the outfits for movies, plays, and television shows, researching exactly what people wore so everything looks authentic and believable.