a person who secretly collects information about a country, organization, or individual, especially for a government or an army
The movie follows a spy who risks everything to stop a war.
During the Cold War, governments planted spies in rival embassies.
✦ From Old French “espie”, related to the verb “espier” (to observe).
to watch or listen to someone or something secretly in order to get information
The detective decided to spy on the suspect's apartment from across the street.
She spied through the keyhole to see what the children were doing.
✦ Derived from Middle English “spien”, from Old French “espier”.
to notice or catch sight of something or someone suddenly
From the hilltop, he spied the distant sails of a ship.
I quickly spied a shortcut through the forest path.
✦ Archaic sense preserved from Old French “espier” meaning ‘catch sight of’.
