A "deadman's brake" is a safety mechanism that engages the brakes on a vehicle when the driver becomes incapacitated or is no longer able to maintain control of the vehicle. Some synonyms for a "deadman's brake" include "safety brake," "fail-safe brake," and "emergency brake." These terms all describe a mechanism that is designed to protect the driver, passengers, and others on the road by preventing a vehicle from continuing to move if the driver is unable to operate it safely. While the term "deadman's brake" may have historical roots, the use of different synonyms highlights the importance of this safety feature in modern vehicles.