: the act of carefully watching someone or something especially in order to prevent or detect a crime
government surveillance of suspected terrorists
The bank robbery was recorded by surveillance video cameras.
electronic surveillance [=the act of using electronic devices to watch people or things]
The police kept her under surveillance. [=watched her closely]
Cite this Entry
“Surveillance.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/surveillance. Accessed 19 Jun. 2026.
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