lockdown

A protocol followed in an emergency that involves confining people in a secure place, such as the confinement of prison inmates in cells after a disturbance, or the locking of students and teachers in classrooms after a violent attack.

A situation in which this protocol is undertaken.

A facility, such as a prison, where people considered to be dangerous are locked inside living quarters or otherwise confined.

The confinement of people in their own rooms (or cells) as a security measure after a disturbance

A contrivance to fasten logs together in rafting.