English Reference
noun · verb

spy

n. · v.
US /ˈspaɪ/ UK /spˈaɪ/ spy UK spelling spied, spies

  1. 01 B1 Intermediate

    n.a person who secretly collects information about an enemy, a government, or a business.

    n.an individual employed by a government or organisation to collect secret information regarding a competitor or enemy.

    Simple

    The spy was caught trying to steal secret documents from the embassy.

    In context

    Intelligence agencies often spend years cultivating a single spy within a foreign government to ensure a steady flow of high-level information.

  2. 02 B1 Intermediate

    v.to watch someone or something secretly to find out information.

    v.to observe a person, group, or country secretly and continuously. Often takes the preposition 'on'.

    Simple

    The children liked to spy on their older brother from the treehouse.

    In context

    The corporation was accused of hiring private investigators to spy on its competitors' research and development facilities.

    Usage

    Commonly used with the preposition 'on' followed by the target.

    snoopsurveilwatch
  3. 03 C1 Advanced Literary

    v.to suddenly see or notice something, especially something far away or hidden.

    v.to catch sight of or detect something through careful observation. Transitive in this sense.

    Simple

    From the top of the hill, she managed to spy a small cottage in the valley.

    In context

    After hours of scanning the horizon with his binoculars, the lookout finally spied a thin plume of smoke rising from the distant island.

  4. 04 C2 Proficiency American EnglishTechnical Sport

    n.a player in American football whose job is to watch and follow a specific opponent.

    n.a defensive player assigned to mirror the movements of a specific offensive player, typically the quarterback, to prevent a run.

    Simple

    The coach decided to use a linebacker as a spy to stop the quarterback from running.

    In context

    By employing a fast linebacker as a spy, the defense successfully neutralised the quarterback's ability to scramble for first downs.

    Usage

    Used as a countable noun in a sports strategy context.

After 9/11, he said, those powers to spy on communities were greatly expanded.

The Guardian· 13 Aug 2026

The FBI discovered former congressman Eric Swalwell’s affair with Chinese spy Fang Fang when the bureau tried to recruit her as an agent, documents say.

Toronto Sun· 17 Aug 2026

From Middle English spien, aphetic variant of earlier espien (“to espy”), from Old French espier (“to spy”), from Frankish spehōn (“to spy”), from Proto-Germanic spehōną (“to see, look”), from Proto-Indo-European *speḱ- (“to look”). Akin to German spähen (“to spy”), Dutch spieden (“to spy”). The noun displaced native Old English sċēawere (literally “watcher”), which was also the word for "mirror." In this sense, the verb displaced Old English sċēawian, which was also the word for "to watch" and became the Modern English word show. Distant cognate vie PIE with Latin speculātor, Ancient Greek κατάσκοπος (katáskopos). Compare typologically Russian согляда́тай (sogljadátaj) (akin to гляде́ть (gljadétʹ)).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin ine-pro *speḱ-
Level C1 · Advanced
Frequency Common
Updated