There's no question in the popular mind that Presidents Lincoln, Garfield,JFK and Mc Kinley were assassinated but assassinations aren't limited to politicians. They can happen to activists (Martin Luther King) and even musicians (John Lennon) How is it decided who's assassinated and who's just plain murdered?
The word assassin according to the Oxford English Dictionary is derived from the word hashshashin which was the name of a secret sect known for the killing of its political enemies. According to legend, members of the sect enjoyed a little pre assassination toking of the hash pipe hence the name Hash. It may not be rooted in truth but looking at some of the mug shots of the assassins it makes you wonder.
The definition in the OED boils down to "killing in a treacherous manner". Treachery indicated a certain amount of plotting and betrayal and is often used in a political sense but it doesn't have to be.
There seems to be 3 major criteria to be considered assassinated.
1.the victim must be well know.
2.he or she must have a political bent.
3.he or she must be the victim of treachery or plotting.
This helps explain why the shooting of Lennon was considered assassination. Lennon was very much a political figure even though he was not a politician.
from How Do Men Think Apandis Publishing
Jan 31, 2010 @ 18:10:03
in assass 
