spy

American  

[spahy] / spaɪ /

noun

plural

spies

1. a person employed by a government to obtain secret information or intelligence about another, usually hostile, country, especially with reference to military or naval affairs.

2. a person who keeps close and secret watch on the actions and words of another or others.

3. a person who seeks to obtain confidential information about the activities, plans, methods, etc., of an organization or person, especially one who is employed for this purpose by a competitor.

   an industrial spy.

4. the act of spying.

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verb (used without object)

spied, spying

1. to observe secretively or furtively with hostile intent (often followed by on orupon ).

2. to act as a spy; engage in espionage.

3. to be on the lookout; keep watch.

4. to search for or examine something closely or carefully.

verb (used with object)

spied, spying

1. to catch sight of suddenly; espy; descry.

   to spy a rare bird overhead.

2. to discover or find out by observation or scrutiny (often followed byout ).

3. to observe (a person, place, enemy, etc.) secretively or furtively with hostile intent.

4. to inspect or examine or to search or look for closely or carefully.

spy British  

/ spaɪ /

noun

1. a person employed by a state or institution to obtain secret information from rival countries, organizations, companies, etc

2. a person who keeps secret watch on others

3. obsolete a close view

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verb

1. to keep a secret or furtive watch (on)

2. (intr) to engage in espionage

3. (tr) to catch sight of; descry

Other Word Forms

• outspy verb (used with object)
• spyship noun
• superspy noun
• unspied adjective
• unspying adjective

Etymology

Origin of spy

First recorded in 1200–50; (for the verb) Middle English spien, shortened from espien, espyen “to espy” ( espy ); (for the noun) Middle English, shortened from espy “a spy,” from Old French espie

Explanation

To spy is to secretly watch someone. It’s not recommended unless you’re actually a spy, a person who is hired by a government or organization to keep tabs on enemies. You might imagine a spy working for the CIA or the KGB, but there are also military spies who infiltrate their opponents' armies to get information, commit sabotage, or steal technology. Private businesses sometimes employ spies as well, to collect information about competitors. As a verb, to spy is to do what a spy does—or simply to see something: "I spy brownies on the kitchen counter!"

Example Sentences

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

Shunammite, the sharpest-tongued of Agnes’ friends, is convinced Daisy is a spy.

From Los Angeles Times • Apr. 8, 2026

It's well known the US regularly flies a U-2 spy plane from RAF Akrotiri, though it's not publicly acknowledged.

From BBC • Mar. 30, 2026

Russia on Monday kicked out a British diplomat over allegations he was working as a spy -- charges rejected by London as "complete nonsense".

From Barron's • Mar. 30, 2026

“And now that Adek was a spy with Olka, it was even worse.”

From "Not Nothing" by Gayle Forman

Related Words

• agent
• detective
• informer
• investigator
• mole
• operative
• secret agent
• secret service
• undercover agent