What is the meaning of Lockdown?

The confinement of people in their own rooms (e.g., in a school) or cells (in a prison), or to their own homes or areas (e.g., in the case of a city- or nation-wide issue) as a security measure after or amid a disturbance or as a non-pharmaceutical intervention in a pandemic.

A contrivance to fasten logs together in rafting.

lockdown (confinement as a security measure)

lockdown

lockdown (confinement of people as a security measure)

Source: wiktionary.org