(military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors
"The intelligence agency confirmed that their new spy had successfully infiltrated the rival company's headquarters to steal proprietary blueprints."
a secret watcher; someone who secretly watches other people
"my spies tell me that you had a good time last night"
A person who secretly watches and examines the actions of other individuals or organizations and gathers information on them (usually to gain an advantage).
"The rival company hired a spy to infiltrate our office and steal our secret product designs before we could launch."
In plain English: A spy is someone who secretly gathers information about another person or group, often for a government or organization.
"The government hired a spy to investigate the scandal."
Usage: Use this noun to describe someone who covertly monitors others, typically in political or military contexts. Distinguish it from "snitch," which implies informing authorities rather than gathering intelligence for strategic advantage.
secretly collect sensitive or classified information; engage in espionage
"spy for the Russians"
To act as a spy.
"She agreed to spy on her rival company by secretly copying their confidential documents during the trade show."
In plain English: To spy means to watch someone secretly without them knowing you are there.
"The detective decided to spy on the suspect from across the street."
The verb spy entered Middle English from Old French, originally meaning to look or see. It eventually replaced the native Old English word sċēawere, which literally meant both a watcher and a mirror.