1. To have a specific involvement or participation in something; to fulfill a role in some undertaking. There's no use lying to the committee, Mr. Marshall, as we know for a fact that you played a part in your company's decision to hide its losses from investors. Listen up, Joe. You're going to play a part in this operation, too.

2. Literally, to portray a certain character in a performance, such as a theater or film production. I hear that Samantha will be playing a part in the director's newest film!