The crossword solution for the term 'lock with no key' is 'TRESS'. A TRESS is a type of lock that does not require a key to open. It is a mechanical device that uses a combination of numbers or symbols to unlock. Tresses are often used in high-security areas, such as banks and government buildings, as they provide an extra layer of security. They are also popular among homeowners who want to keep their valuables safe without having to worry about losing a key.