- Close observation, especially of a suspected spy or criminal: he found himself put under surveillance by military intelligenceMore example sentences
- An unpolitical lad is blackmailed by the police into doing undercover surveillance in a mosque.
- It is understood police had the suspects under surveillance for weeks before the robbery.
- For years, undercover surveillance was the domain of warring couples and the old DHSS.
early 19th century: from French, from sur- 'over' + veiller 'watch' (from Latin vigilare 'keep watch').