- a watch kept over a person, group, etc., especially over a suspect, prisoner, or the like: The suspects were under police surveillance.
- continuous observation of a place, person, group, or ongoing activity in order to gather information: video cameras used for covert surveillance.
- attentive observation, as to oversee and direct someone or something: increased surveillance of patients with chronic liver disease.
- close observation or supervision maintained over a person, group, etc, esp one in custody or under suspicion
