On __; Confined as a Security Measure
Puzzle 15 of Aquarium Easy Pack
Question is: On __; Confined as a Security Measure
and the answer is: LOCKDOWN
Word Meaning:
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.
Definitions from Wiktionary.