Ragnarok Online Job Class, see nerfed

A person whose assignment is to kill. Typically, the person is paid to do the job well.

A large game played over an extended period of time, usually by 10 or more people, and typically set in a college dorm. Players are secretly assigned the name of another player to "assassinate," that is, squirt with a water gun when the target is not looking and when no one else may see the shot. When the target is assassinated, the assassin inherits the target of the deceased, thus closing the circle. The game continues until only one assassin remains.

A hardcore ninja that doesn't care for all that Natrutard crap.

a person who has the reflexes of a cat, balls of steel and a head full of nothing, walks up to or next to a girl(preferably in a public or crowded area) and so fast and quietly slaps the girls ass when she turns to slap or spot the man...he has already vanished into the crowd using ancient blending techniques honed over countless days of playing only assassins creed!

1) noun. Assassins were first referred to as Hashashins because they were given hashish and taken into a little garden slice of paradise. They were then told that if they died in their lord's service they would automatically return in death to this paradise, and have a harem of women. This was eventually shortened to assassins.
2) Adverb. To whoop some dude's ass with Kungfu grip.

A trained killer hired for money to kill other people.

Assassin is also a song by the rock band Muse, it is probably the heaviest song on their new album

1. (Noun): a person who is hired to kill someone for money
2. (Noun): a person who kills someone because they don't like that person
3. (Proper Noun; Fiction(maybe): A member of an ancient order that is at constant war with the Knights Templar, where the largest battles are highlighted by the game series Assassin's Creed.
!!!SPOILERS!!!
The first Assassins were Adam and Eve as reveiled in The Truth