Meaning
A trick that smuggling past a defence what could never breach it openly - a person, plan, or program welcomed inside on innocent pretences that then attacks from within. In computing it names malicious software disguised as something useful, and in politics any measure whose real purpose hides inside an attractive one. Capitalized traditionally for the myth; style guides now allow lowercase for the malware sense. In computing keep the distinction from virus and worm sharp: a trojan is invited in. Regional use: General English; classical origin, modern computing sense.
Origin
The wooden horse of Troy is absent from the Iliad and glimpsed only briefly in the Odyssey, which credits its building to Epeius with Athena's help; the fullest account is Book II of Virgil's Aeneid (19 BC), where the Greeks feign departure, Sinon persuades the Trojans the horse is an offering to Athena, and Laocoon's warning - I fear Greeks, even those bearing gifts - is silenced by serpents. Art predates the poems: the Mykonos vase (750-650 BC) shows the warriors inside. The computing industry borrowed the name early: the first Unix manual of 3 November 1971 warned that without protection one could create Trojan Horses able to misuse other's files, a 1974 Air Force report on Multics discussed guarding against them, and Ken Thompson's 1983-84 Turing lecture, Reflections on Trusting Trust, made the term famous. Unlike a virus or worm, a trojan cannot spread itself; it relies on being welcomed, which is the whole point of the name.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- a Trojan horse
- Trojan horses
Usage Examples
- The merger looked like a rescue and proved a Trojan horse; within a year the whole board was theirs.
- Security researchers warned the free PDF tool was a Trojan horse harvesting tax files.
- Critics called the bill a Trojan horse, its Schedule 3 doing more than the friendly title promised.