lockdown

UK: /ˈlɒkdaʊn/ US: (lok′doun′)

WordReference Random House Unabridged Dictionary of American English © 2026

lock•down  (lok′doun′), n. 

1. the confining of prisoners to their cells, as following a riot or other disturbance.

• lock¹ + -down, probably extracted from nouns formed from phrasal verbs, such as crackdown, shutdown, etc. 1970–75

Collins Concise English Dictionary © HarperCollins Publishers::

lockdown / ˈlɒkˌdəʊn/ noun

1. a security measure in which those inside a building or area are required to remain confined in it for a time: keepers put the park into lockdown while they tracked down the baboon
2. the imposition of stringent restrictions on travel, social interaction, and access to public spaces: the government imposed a national lockdown to prevent the spread of the virus