Final answer:
Fox, Levin, and Fridel's definition of a serial killer characterizes an individual committing planned multiple murders over time for psychological gratification, as distinct from other forms of homicide like vigilante justice.
Step-by-step explanation:
The definition of a serial killer according to Fox, Levin, and Fridel encompasses an individual who commits a series of murders over a period of time, typically with cooling-off intervals between them. The crimes are usually driven by abnormal psychological gratification, and the victims may have certain commonalities that reflect the psychological motives of the killer. This distinct form of murder is characterized by the killers pursuing their victims within a predictable framework, often involving a combination of planning and compulsion.
Serial killings are often juxtaposed against other forms of homicides, like those conducted by angry lynch mobs, which might not fall into the same category. It's imperative to note that while vigilante justice and crowd sanctioned violence as historically seen in lynch mobs involve community participation and are directed at supposed wrongdoers, serial killings are deeply individual acts often enveloped in secrecy and personal psychopathology.