Trojan horse

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.
a nonreplicating computer program planted illegally in another program to do damage locally when the software is activated.
British Dictionary definitions for trojan horses

Trojan Horse

noun
1.
(Greek myth) Also called the Wooden Horse. 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
trojan horses in Culture

Trojan Horse definition


In classical mythology, a large, hollow horse made of wood used by the Greeks to win the 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.

Note: The story of the Trojan horse is the source of the saying “Beware of Greeks bearing gifts.”
Slang definitions & phrases for trojan horses

Trojan horse

noun phrase

A kind of computer virus: ''Trojan horse'' programing lies in wait to be triggered later, either at a certain day, hour, or minute or when system use or storage reaches a certain level

[1990s+ Computers; fr the wooden horse full of soldiers used by the Greeks to end the siege of Troy]