American Heritage Dictionary
(3)
Century Dictionary
GNU Webster's 1913
WordNet
(1)
Elsewhere on the web
Holly Shelton, spokeswoman for the Amarillo Independent School District, said the principal determined the lockdown was the best course of action.
The courthouse immediately went on lockdown, although people were allowed to leave after the building was secured, McConnell said.— The Seattle Times
"There is no curfew because that would imply a state of lockdown which is not the case," he said.— Fiji Times Online - Local News
And on Thursday morning, a lockdown was ordered when three men officials believe were involved in the incident came onto campus.

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