What is meant by a "lockdown" in a correctional facility?

A "lockdown" in a correctional facility refers to a security measure implemented to confine inmates in response to specific threats, whether they arise from internal or external situations. During a lockdown, movement within the facility is restricted to ensure the safety of both staff and inmates. This could be due to various reasons, such as a potential escape, a riot, or the discovery of contraband. The focus during a lockdown is on maintaining control and ensuring security until the threat can be assessed and resolved.

The other options describe actions or statuses that do not precisely align with the definition of a lockdown. Permanent confinement of inmates is a characteristic of incarceration, while a routine check of inmate cells involves regular inspection for safety and security, and disciplinary actions are responses to rule violations, none of which capture the immediate and protective nature of a lockdown.