trojan horse has 3 distinct synonyms spread across 3 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a subversive group that supports the enemy and engages in espionage or sabotage; an enemy in your midst
a program that appears desirable but actually contains something harmful
“the contents of a trojan can be a virus or a worm”
Synonyms, antonyms and the broader and narrower relations for trojan horse come from Princeton University’s WordNet. Full sources and licences.
a large hollow wooden figure of a horse (filled with Greek soldiers) left by the Greeks outside Troy during the Trojan War