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Definitions

spy

[spahy] / spaɪ /
NOUN
person who secretly finds out about another's business
Synonyms
STRONGEST
agent detective informer investigator mole operative secret agent secret service undercover agent
STRONG
emissary lookout observer patrol plant scout sleeper sleuth snoop spotter watcher
WEAK
double agent espionage agent foreign agent inside agent intelligencer plumber
VERB
secretly follow, watch another's actions
Synonyms
STRONGEST
discover examine scrutinize snoop
STRONG
case eyeball glimpse meddle notice observe peep pry reconnoiter scout search shadow sleuth spot stag tail trail view watch
WEAK
catch sight of fish out get a load of keep under surveillance look for recon set eyes on stake out take in take note
Antonyms
STRONG
ignore miss neglect overlook

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Officials thought vulnerabilities in their software could provide China access to spy on U.S. communications or access sensitive infrastructure.

From The Wall Street Journal • Apr. 10, 2026

Healey told a Downing Street press conference on Thursday that Russia had sent an Akula class submarine as a diversionary tactic while two of its Guggi spy submarines carried out the surveillance of these cables.

From BBC • Apr. 9, 2026

In “The Testaments,” Lucy Halliday stars as Daisy, a new Pearl Girl who is really an undercover spy for Mayday.

From Los Angeles Times • Apr. 8, 2026

Fourth place went to Hindi-language spy thriller "Dhurandhar: The Revenge" with $4.75 million.

From Barron's • Mar. 29, 2026

When I arrived at my usual spot to spy on the Americans, suspicious activity was going on.

From "The (Mostly) True Story of Cleopatra's Needle" by Dan Gutman

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