1. Very annoying hacking program.
2. AOL
"I used to have a really popular trojan called aol."
by manutdfan4life February 13, 2005
1)Citizen of Illion(Troy)
2)Computer hacking program
3)Someone who is a double-crosser
"I hacked that Trojan with my new trojan software however it turned out the person who gave it me was a Trojan"
by Stephen April 9, 2004
A piece of software to gain access to a computing system, while the owner isn't aware of it's existence.
Often introduced in a system hidden in an appealing looking free paquage or a free game.

In essence the same principle as the "Trojan horse" which Odysseus used to conquer Troy.
"I planted a trojan in her system, I even have access to her webcam now!"
"You really should get a life, dude!"
by BelgainDSoul August 10, 2003
Someone who wasn't accepted to UCLA.
I hope that someday I don't have to settle for being a Trojan...
by God January 17, 2005
An undesirable person that makes friends with a nice person in order to get in to parties and other social circles and events. As in using nice people in the manner of a Trojan Horse to gain access to places they would not be invited normally.
We were going to invite Jeff to the party, but Michelle will totally Trojan.
by no means no July 2, 2012
A make of condom or shealth used to prevent the transition of semen from a man to a woman, man or animal.
"Yeah mate, I whacked on the ol' Trojan and did her in the batty"
by Link December 8, 2004