an official order to control the movement of people or vehicles because of a dangerous situation （对人或交通工具的）活动限制，行动限制 a three-day lockdown of American airspace 美国为期三天的领空关闭 Prisoners have been placed on lockdown to prevent further violence at the jail. 已对囚犯实行活动限制，以免狱中再出现暴力行为。 🔊🔊 The prison governor ordered an instant lockdown (= prisoners were locked in their cells). 监狱长下令立即封锁。 The city schools were in lockdown. 城市学校处于封锁状态。