A device, mechanism or measure designed to make something fail-safe.

To compensate automatically, in the event of a failure. / To make a device or mechanism fail-safe, or to add a fail-safe device or mechanism to an existing system.

A document that grants safe passage through enemy territory in times of war. / A convoy or guard to protect a person in a foreign country.

(obsolete) To guarantee safe passage by granting such a document.

The security given by authority of a government to a stranger for his quietly coming into and passing out of the territories over which said government has jurisdiction or control.

Safe enough to store valuables securely

A safe-deposit box

Alternative form of dishwasher-safe

Safe to use in microwave ovens.

To take a cautious, risk-free approach.