For those who have trouble "defining" a sociopath I refer you to: http://www.minddisorders.com/Flu-Inv/Hare-Psychopathy-Checklist.html

From the site:

The Hare PCL-R contains two parts, a semi-structured interview and a review of the subject's file records and history. During the evaluation, the clinician scores 20 items that measure central elements of the psychopathic character. The items cover the nature of the subject's interpersonal relationships; his or her affective or emotional involvement; responses to other people and to situations; evidence of social deviance; and lifestyle. The material thus covers two key aspects that help define the psychopath: selfish and unfeeling victimization of other people, and an unstable and antisocial lifestyle.

The twenty traits assessed by the PCL-R score are:

glib and superficial charm
grandiose (exaggeratedly high) estimation of self
need for stimulation
pathological lying
cunning and manipulativeness
lack of remorse or guilt
shallow affect (superficial emotional responsiveness)
callousness and lack of empathy
parasitic lifestyle
poor behavioral controls
sexual promiscuity
early behavior problems
lack of realistic long-term goals
impulsivity
irresponsibility
failure to accept responsibility for own actions
many short-term marital relationships
juvenile delinquency
revocation of conditional release
criminal versatility

The interview portion of the evaluation covers the subject's background, including such items as work and educational history; marital and family status; and criminal background. Because psychopaths lie frequently and easily, the information they provide must be confirmed by a review of the documents in the subject's case history.

Read more: Hare Psychopathy Checklist - define, person, people, used, personality, score, traits, Definition, Purpose http://www.minddisorders.com/Flu-Inv/Hare-Psychopathy-Checklist.html#ixzz1dulG16hI

When considering that there are different "levels" of severity for each trait and understanding that socipathy, like most mental and/or personality disorders, exists on a continuum from mild but still a sociopath (so those who don't go on torture, rape and killing sprees but are generally untrustworthy rat bastards) to full blown murdering psycho I really don't have a problem with understanding this terminology.