Trojan horse


Definition of Trojan horse

1 : someone or something intended to defeat or subvert from within usually by deceptive means
2 : a seemingly useful computer program that contains concealed instructions which when activated perform an illicit or malicious action (such as destroying data files) also : the concealed instructions of such a program — compare virus sense 3

Did you know?

After besieging the walls of Troy for ten years, the Greeks built a huge, hollow wooden horse, secretly filled it with armed warriors, and presented it to the Trojans as a gift for the goddess Athena, and the Trojans took the horse inside the city's walls. That night, the armed Greeks swarmed out and captured and burned the city. A Trojan horse is thus anything that looks innocent but, once accepted, has power to harm or destroy—for example, a computer program that seems helpful but ends up corrupting or demolishing the computer's software.

Examples of Trojan horse in a Sentence

They may be using the other corporation as a Trojan horse.

First Known Use of Trojan horse

1837, in the meaning defined at sense 1

History and Etymology for Trojan horse

from the large hollow wooden horse filled with Greek soldiers and introduced within the walls of Troy by a stratagem

Learn More About Trojan horse

Time Traveler for Trojan horse

Time Traveler

The first known use of Trojan horse was in 1837

See more words from the same year

Dictionary Entries Near Trojan horse

Trojan group

Trojan horse

Trojan War

See More Nearby Entries 

Statistics for Trojan horse

Cite this Entry

“Trojan horse.” Dictionary, Merriam-Webster, Accessed 28 May. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

More from Merriam-Webster on Trojan horse

Thesaurus: All synonyms and antonyms for Trojan horse

Nglish: Translation of Trojan horse for Spanish Speakers


Test Your Vocabulary

Which Word Does Not Belong?

  • one green toy robot amidst many red toy robots
  • Which of these words does not mean "nonsense"?
True or False

Test your knowledge - and maybe learn something along the way.

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!