lockdown

[ lok-doun ]
/ ˈlɒkˌdaʊn /

noun

the confining of prisoners to their cells, as following a riot or other disturbance.
a security measure taken during an emergency to prevent people from leaving or entering a building: The school remains under lockdown due to police activity in the area.

Origin of lockdown

1970–75; lock1 + -down, probably extracted from nouns formed from phrasal verbs, such as crackdown, shutdown, etc.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for lockdown

British Dictionary definitions for lockdown

lockdown
/ (ˈlɒkˌdəʊn) /

noun

US a security measure in which those inside a building such as a prison, school, or hospital are required to remain confined in it for a timemany schools remained under lockdown yesterday
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012