An action taken or a mechanism put in place to avoid a disaster. Fail-safe does not mean that something is unable to fail (the term used for this is fail-secure), but instead means that if something does fail, the device will do whatever possible to minimize the negative outcomes. Many forms of transportation will include fail-safe mechanisms, which in the event of a potentially problematic mechanical malfunction, will operate in a way which does everything possible to ensure the safety of the travelers.