1. a person who uses illegal drugs or performance-enhancing drugs
Usage: informal; often used in sports contexts
2. a substance used to enhance the performance of semiconductors or other materials in electronics
Usage: technical; physics and engineering

Examples

• The athlete was banned from competition after being identified as a doper.
• Several cyclists admitted to being dopers during the investigation.
• The doper was added to the silicon to increase its conductivity.
• In semiconductor manufacturing, a doper changes the electrical properties of the material.
• The coach warned his team that dopers would face serious consequences.