spy2 past tense and past participle spied, present participle spying, third person singular spies
to secretly collect information about an enemy country or an organization you are competing against
He was charged with spying on British military bases.
He confessed to spying for North Korea.
2 [transitive] literary
to suddenly see someone or something, especially after searching for them [= spot]:
Ellen suddenly spied her friend in the crowd.
spy on somebodyphrasal verb
She sent you to spy on me, didn't she?
spy something ↔ outphrasal verb
to secretly find out information about something
2 British English
to secretly find out more information about a situation before deciding what to do