a person employed to find out secret information, especially from an enemy or a competitor in business
act as a spy on; watch secretly
observe; see; discover
"my spies tell me that you had a good time last night"
"he caught sight of the king's men coming over the ridge"
"spy for the Russians"
Miss Octavia, spying her through the blinds, came down..to meet her.
出自： W. March
The old lady likes spying into other people's affairs.
He was paid by the police to spy on other students.