the act of confining prisoners to their cells (usually to regain control during a riot)

A lockdown is an emergency protocol to prevent people or information escaping, which usually can only be ordered by someone in command. They are also used to protect people inside a facility from a dangerous external event: schools practice lockdown drills in the wake of the Columbine High School shootings in which students with guns entered the school; or from an internal event: prison facilities also practice lockdown procedure on their inmates when faced with rioting or unrest. It is a common anti-terrorism measure in the wake of an atrocity and a popular plot-device in fiction.

"Lockdown" is the 41st episode of Lost. It is the seventeenth episode of the second season. The episode was directed by Stephen Williams, and written by Carlton Cuse & Damon Lindelof.

Lockdown is a 2000 drama film, starring Richard T. Jones, Clifton Powell, and Master P.

a close contender for PPV of the year, I'd say

Lockdown is a utility application written in Visual C#. It offers such features as file wiping, password generation, encryption, and hopefully will expand to include more. It is still in beta however, and should be used ONLY for testing at the moment.