spy

To watch someone secretly and find out what they do.

• Are you spying on me?
• He spied on his neighbours from the window.
• The children tried to spy through the fence.

How to use it: spy on someone (Stop spying on your neighbours.); spy through something (He spied through a gap in the curtains.)

Common phrases: spy on someone, spy through something

To secretly collect information for a country or organization.

• He was paid to spy.
• She spied for her country for years.
• The agents were spying on a rival company.

How to use it: spy for someone/something (He spied for a foreign intelligence service.); spy on someone/something (They were accused of spying on the government.)

Common phrases: spy for someone, spy on someone

To notice or suddenly see someone or something.

• I spied a bird in the tree.
• She spied her brother across the crowded room.
• Can you spy a figure on the hill?

How to use it: spy someone/something doing something (We spied a deer crossing the path.)

Similar words: spot, notice, catch sight of

Common phrases: spy someone ahead, spy something nearby, spy someone approaching, spy something outside

A person who secretly collects information for a country or organization.

• The spy stole secret documents.
• They caught two spies near the military base.
• She worked as a spy during the war.

How to use it: a spy for someone/something (He was a spy for a foreign government.)

Similar words: secret agent, intelligence agent

Common phrases: enemy spy, foreign spy, a secret spy

Someone who secretly watches other people to learn what they are doing.

• There is a spy at the window.
• She feared a spy would photograph her private meeting.
• He accused his neighbour of being a spy.

Common phrases: a hidden spy, a nosy spy