Definition of "lockdown" []

• The confinement of prison inmates to their cells as a security measure following a disturbance in the prison. (noun)
• A prison, especially a high-security one. (noun)
• A device that secures a piece of equipment, especially a computer, so that it cannot be moved or stolen. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "He never really had to go into what I call lockdown."
• "And the school is under what they call lockdown, with no one being allowed in or out of the school."
• "Not surprisingly, shortly after Google+ made its debut, Zuckerberg flipped on a pink neon sign at headquarters with the word lockdown, signaling that employees were on notice to work around the clock on, among other things, replicating some of the most praised Google+ features."