Trepan is a term used to describe a surgical procedure in which a hole is drilled or scraped into the skull. It was used in ancient times to treat health problems related to the brain, such as seizures and mental disorders. The crossword solution for trepan is 'ENTRAP, ' which means to catch someone in a difficult situation from which they cannot escape. This term is often used to describe a situation in which someone is tricked or manipulated into doing something they don't want to do.