Why do they call serial killers serial killers?

Answer 1

Serial means a series of crimes, usually one at a time, with a 'cooling off' period in between kills. The cooling off time depends on the individual killer. Jack The Ripper killed two women in the space of an hour. Some killers may not kill again for several years.

Answer 2

serial killers are in fact rational planners in most times. Only holliwood portray serial killers as rational killers. They commit the worst irrational killings. Killing a witness or a revenge killers is concidered a more rational killings. Serial killers go beyond the point that they write notes to the authorities.

The reason about this is that serial killers try explain their crimes as rational at the time they get personal gratitud to brag about the crime.

Only in movies, serial killers commit rational killings.