surveillance
surveillance — noun
1. the activity of closely watching people, buildings, or areas to prevent or solve
the activity of closely watching people, buildings, or areas to prevent or solve crimes and to collect information for security purposes
Surveillance of the warehouse showed workers leaving goods by the back door at night.
The bank manager was kept under police surveillance for three days after the robbery.
collocation: under surveillance
Police surveillance of the area increased after several cars were stolen last month.
Surveillance cameras on the corner recorded a man taking packages from parked cars.
Electronic surveillance of their phones helped catch the group before the robbery.
- monitoring
broader term; can refer to routine or technical observation (e.g., health monitoring), not only for crime prevention
- observation
more neutral and general; used in science, medicine, and everyday contexts, not necessarily secretive
- watch
informal and shorter; often used in 'keep watch' or 'under watch,' less technical than surveillance
文法句型
under + surveillance
surveillance + noun (as modifier)
用法筆記
Uncountable noun — do not say 'a surveillance' or 'surveillances.' The idiomatic pattern is 'keep someone/something under surveillance.' Also commonly used as a modifier before nouns ('surveillance camera,' 'surveillance footage').