to dress up as; to disguise oneself as; to play the role of
彼は悪役に扮している。
He is playing the role of a villain.
女優が修道女に扮した演技が評判になった。
The actress became known for her performance as a nun.
探偵は依頼人に合わせて老人に扮する。
The detective disguises himself as an old man to match his client's needs.