How important does a person have to be to be considered assassinated instead of murdered?

Assassinate merely means to kill suddenly or secretively, especially a politically prominent person; murder premeditatedly and treacherously. It's no different to premediatated murder but people tend to use it as a term for famous premeditated murders such as Lennon and Kennedy.

A political figure is said to have been assassinated, ( kennedy, martin luther king, robert kennedy, lincoln etc) anyone else is murdered, like john lennon,versace, people like that.

Traditionally assassinated means they were a politician or political leader (dictator/king?) and some social movement leaders are so politically effective that they are considered assasinated when killed.

The victim should be well-known, popular commanding a column or two in print media & a few seconds on TV shows or news. .

According to the dictionary, they have to score at least a 74 on the 98-point Importance Scale.

About so <hold forefinger and thumb apart>.