catch sight of; to perceive with the eyes

secretly collect sensitive or classified information; engage in espionage

(military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors

a spy who makes uninvited inquiries into the private affairs of others

secretly collect sensitive or classified information; engage in espionage

secretly collect sensitive or classified information; engage in espionage

a secret watcher; someone who secretly watches other people

To look and wait expectantly or in anticipation, To stay awake at night while serving as a guard, sentinel, or watcher, To guard, keep surveillance on, or spy on, noun_ The period of time during which one person or body of persons watch or stand sentinel, or the time from one relief of sentinels to another; hence, a division of the night, when the precautionary setting of a watch is most generally necessary; period of time; hour, The state of being awake; wake-fulness, The members of a ship's crew on duty during a specific watch

Software that secretly gathers information about a person or organization, Internet programs that surreptitiously monitor and report the actions of a computer user, computer software that obtains information from a user's computer without the user's knowledge or consent

One who secretly collects information concerning the enemies of a government or group, One who secretly collects information for a business about one or more of its competitors, a secret watcher; someone who secretly watches other people, verb_ catch sight of, secretly collect sensitive or classified information; engage in espionage, watch, observe, or inquire secretly, transitive verb_ To gain sight of; to discover at a distance, or in a state of concealment; to espy; to see, To discover by close search or examination, To explore; to view, inspect, and examine secretly, as a country; -- usually with out, intransitive verb_ To search narrowly; to scrutinize, To engage in espionage, To discover by close observation