Main Entry: Trojan horse

Function: noun

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

Date: 1837

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 (as destroying data files); also : the concealed instructions of such a program — compare virus