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• Trojan horse
  Trojan horse

  noun

  a gigantic hollow wooden horse, left by the Greeks upon their pretended abandonment of the siege of Troy. The Trojans took it into Troy and Greek soldiers concealed in the horse opened the gates to the Greek army at night and conquered the city.
• Trojan Horse
  Trojan Horse

  noun

  Greek myth the huge wooden hollow figure of a horse left outside Troy by the Greeks when they feigned retreat and dragged inside by the Trojans. The men concealed inside it opened the city to the final Greek assault

Trojan horse

American  

[troh-juhn hawrs] / ˈtroʊ dʒən ˌhɔrs /

noun

1. Classical Mythology. a gigantic hollow wooden horse, left by the Greeks upon their pretended abandonment of the siege of Troy. The Trojans took it into Troy and Greek soldiers concealed in the horse opened the gates to the Greek army at night and conquered the city.

2. a person or thing intended to undermine or destroy from within.

3. Also called Trojan.  Computers. a nonreplicating computer program planted illegally in another program to do damage locally when the software is activated.

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Trojan Horse British  

noun

1. Also called: the Wooden Horse.  Greek myth the huge wooden hollow figure of a horse left outside Troy by the Greeks when they feigned retreat and dragged inside by the Trojans. The men concealed inside it opened the city to the final Greek assault

2. a trap intended to undermine an enemy

3. computing a bug inserted into a program or system designed to be activated after a certain time or a certain number of operations

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Trojan Horse Cultural  

1. In classical mythology, a large, hollow horse made of wood used by the Greeks to win the Trojan War (see also Trojan War). The resourceful Odysseus had come up with the plan for the horse. The Greeks hid soldiers inside it and left it outside the gates of Troy. They anchored their ships just out of sight of Troy and left a man behind to say that the goddess Athena would be pleased if the Trojans brought the horse inside the city and honored it. The Trojans took the bait, against the advice of Cassandra and Laocoon. That night the Greek army returned to Troy. The men inside the horse emerged and opened the city gates for their companions. The Greeks sacked the city, thus winning the war.

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Discover More

The story of the Trojan horse is the source of the saying “Beware of Greeks bearing gifts.”

Etymology

Origin of Trojan horse

First recorded in 1570–80, in 1835–40 Trojan horse for def. 2, and in 1970–75 Trojan horse for def. 3

Example Sentences

See Examples For:

Trojan horse Trojan Horse

"It's been a kind of Trojan horse for bad development," Owen Espley, the group's community campaigns manager, told AFP.

From Barron's ● Sep. 8, 2026

He’s made a movie about Odysseus’ remorse for inventing the Trojan horse without a crucial scene: the moment he invents it.

From Los Angeles Times ● Aug. 4, 2026

Meanwhile, Time is helping advertisers get their messages in front of bots, using a sort of Trojan horse approach—creating text-based ads that regular readers never see but that AI crawlers might find.

From The Wall Street Journal ● Jul. 22, 2026

Scientists refer to this as a Trojan horse effect, and the researchers say it may also play a role in the spread of antibiotic resistance.

From Science Daily ● Jun. 6, 2026

Once the all-purpose solution, Washington was now the still-potent problem, a kind of Trojan horse planted squarely in the Virginia fortress.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis

Adapted from Homer's ancient Greek poem, The Odyssey will star Matt Damon, Tom Holland, Anne Hathaway and Zendaya, and Nolan played a key section of the film featuring the Trojan Horse at CinemaCon.

From BBC ● Apr. 17, 2026

Samary assembled a Trojan Horse rescue force, stuffed with mutineers, and left for Issa’s house.

From The Wall Street Journal ● Mar. 12, 2026

Cassandra A ancient Trojan priestess who was fated to be a prophet but never believed, most famously about Greek troops hiding inside the Trojan Horse.

From Los Angeles Times ● Apr. 19, 2024

In one scene, guards allow the Trojan Horse to enter the city of Troy after twisting open an Oreo.

From Salon ● Feb. 11, 2024

“And I think there’s a Trojan Horse right next to it.”

From "The Seven Wonders of Sassafras Springs" by Betty G. Birney