Other forms: lockdowns
A lockdown is when people are restricted to a specific area for safety reasons. When incarcerated people are put on lockdown, they're usually confined inside their cells.
Prisons and jails use lockdowns to ensure that inmates and guards are safe, and schools use them the same way, as a response to a threat of danger. During a building lockdown, no one is permitted to enter or leave. Public health lockdowns are a variation on this; the perceived threat isn't violence, but a contagious disease, and staying home reduces the rate of spread. Lockdown originated from the prison meaning and its literal locked cells.