So, the bare minimum definition:

A person who has a significantly reduced ability to experience empathy, as the result of
psychological trauma.

To get into more detail, sociopathy arises when a deep bond shared with someone is broken
by the person with whom it is shared. It's a betrayal that can never be rectified. The trauma
said person caused is one that can't be rationalised or justified. We can't make sense of it,
but we know we are not the ones to blame. A personal conflict arises. We are the victim of
someone who we had such trust in. We can't recover from that, so we change. We adapt to
expect this behaviour from anyone - after all, if the person we bonded with can cause such a
thing, what the fuck will stop anyone else in the world? It becomes a game to us - the world,
life, people. We've seen how ugly it can be, so we're prepared to be just as ugly if and when
we need to. We don't feel sorry because there was no one to feel sorry for us. Fuck your
feelings.

Now, there are two types - high functioning and low functioning. Each type generally
operates in the opposite way. Here's a basic HFS vs LFS breakdown.

 Controlled vs uncontrolled behaviour.

 Skilful deception vs obvious lying.
 Automatic (don't need to think before acting) vs manual (has to think about every
step) actions.
 I would include great planners vs poor planners, but I'm an INPT so it's hard to tell
where the planning skill ends for one and starts for the other.

HF and LF can also be applied to psychopaths and machiavellians. Things both HFS and
LFS share:

 Extreme rage when triggered.

 Compulsions to complete an objective when set.
 Lack of interest in others' problems.
 Prioritising of self-interests.
 Ego - more than a normal person, less than a narcissist.
 Desire for power - not usually over people but over situations, which often involves
the manipulation of people. We control situations.
 We let you in to gain your trust. We'll tell you a lot of things about us - LFSs will
usually include lies, HFSs will usually masterfully tell you the truth - because it
gets you to open up.
 Make no mistake, we have trust issues and we generally won't trust you - for a
good while, at least, if ever. We may give you a chance to prove yourself and we
may just take a risk, whether we care about your trustworthiness or not, but don't
have any high expectations.
 Disregard for rules and social norms. We march to the beat of our own drum and
create our own "code" that we live our lives by. I can't begin to tell you how
annoying this code can be at times but it saves us from so much additional
bullshit. (I can personally testify that every time I have broken my own rules, it has
taken me down a road that could have easily been avoided.)
 We are not rebels. We don't go against the system because a system is there to go
against, we just do what we want, regardless of the side of the fence upon which it
sits.
 We can (and will) rationalise absolutely anything we want to do.
 We are obsessive.
 We are efficient. We don't like to do things that will take longer than necessary.
This is why we are seen as "lazy". We just don't like wasting time on shit we have
no interest in.
 We plan - it helps with our efficiency.
 We don't "practice" fitting in. It's not like we are forever feeling compelled to do
crazy and horrific shit. We just do what we know as best we can. Psychopaths are
the actors, not us.
 To elaborate on being an “actor”: Most people mistake acting for appropriate
behaviour or social convention. Smiling and all of that is fine, it doesn't change
who you are. That's simply you getting by in the world. This is completely different
to the genuine acting of psychopaths, just like actors in real life, who develop
entire personas to base an identity around. That type of acting is way too much
effort to keep up.
 We have the ability to not care about a great many things - this does not mean that
we don't care about anything. That is a myth. What we care about depends on the
nature of an individual, as well as their personality. What you do need to realise is
that we tend to have a low to no level of care for the things society expects people
to care about, such as death (in general), maliciousness, greed and so on.
 We feel empathy over the weirdest shit. I can empathise with a character in a TV
show for a reason I wouldn't give a shit about in real life. I've never actually
understood why, but I have a theory that I explain later on in this answer.
 We feel emotions. What we can also do is significantly suppress emotion in a given
moment.
 We can emulate emotional responses to a degree if we feel the need to, but we
don't usually see the need to. What does happen, however, is that regardless of
outward appearance, we absolutely never believe that shit ourselves. The feeling
inside is so hollow it's hilarious; you know just how much bullshit you are slinging
in that very moment.
 Sociopaths are not sadistic. Sadistic sociopaths, however, are.
 We give objective advice to help you fix problems so you can stop telling us about
it. It usually isn't sugar-coated and may not be what you want to hear, but such is
life. Unless we need to keep you in a specific state, that is.
 Serious issues maintaining relationships. People have to accept us as we are. Most
relationships are on borrowed time the moment they begin because, unlike
psychopaths, we can't act like we give a shit.
 It is possible for us to not be sociopathic with the few people we are able to bond
with. The happening of a bond is never within our control, which is a bloody pain.
You just feel different about the person and it can happen the moment you meet
someone. Again, something I can't fully explain.
 We CAN love in a romantic way. We can love very hard, in fact, due to obsession,
but our love is not expressed in the same way as most people. It's more accurate to
measure whether or not we love you by assessing how we treat you compared to
other people. We can also do romantic things because we know what is considered
 romantic. Some sociopaths just don't make the effort, just like some "normal"
people.
 No conscience. We know and understand right from wrong... We just don't care.
 Following on from the above point, when rationalisation/justification has been
established but we wonder if it what we did was the best course of action to take,
we experience something that can appear similar to guilt but it's not guilt; more
“indeterminable retrospective conflict”. It can be a bitch on the mind, too.
 We do anything to get what we want.
 We are scarily consistent.
 We are loners and exist in our own world. Whether we are isolated or in a crowd,
we just look at you through the window of our own invisible room.
 We don't necessarily hate the world; thinking we do is a common misconception.
In fact, we don't hate the world at all. That would bear too much emotion in us,
which isn't possible. I, for one, can like people individually but don't like people in
general - that's because I'm misanthropic. We accept the world for what it is -
however one may view it - and we just move through it however we feel is
necessary for satisfaction.
 No, we aren't empty inside. If you meet one who is, that's them as a person, not
them as a sociopath.
 We are neither good or bad, but we are both. Just like normal people. It all
depends on the nature of an individual in question.
 Lastly, a sociopath will deny, ignore or accept the fact that they are one. No
sociopath will ever sit around bitching and moaning and crying about the fact that
we are one. We won’t wish to change. We won’t seek ways to raise empathy levels.
We won’t hope a psychologist/psychiatrist/therapist can find a way to change our
personality.

We share many characteristics and traits with psychopaths but the perspectives are
different. The desire for power, as an example. Sociopaths want to control a situation while
psychopaths, from what I've seen, want to control the people. They can both lead to the
same place but the approach is different. Machiavellians, well they just aim to control
everything because manipulation is their ball game above the other dark triad personalities.

Sociopathy isn't one of the dark triad personalities as it's classed as a subset of psychopathy
but, in my opinion, it places somewhere between psychopathy and machiavelliansm, but
within the psychopath half. Thinking about it, the distance between psychopathy and
machiavellianism may actually be the scale of sociopathy, based on the amount of empathy
one can express, since sociopathy is not absolute. I guess the nature of our creation allows
experience prior to our change to have some bearing on the degree to which sociopathy
changes us - I do know that the later in life you become one, the easier it is to fit in. One can
assume that's based on you spending X amount of years following social norms.

Sociopathy is not a coping mechanism, nor one of defense.

 A coping mechanism implies that the cause is still being experienced, and would
mean we use sociopathy to reduce the feeling, like when you are experiencing
physical pain and tense up. When the pain is gone, you relax. This is not what is
happening. The event that changed us is gone. We don't relive the experience
constantly, so there's nothing to "cope" with.
  A defence mechanism is one that we use as a shield. Sociopathy isn't a shield. We
aren't guarded against the world. We don't feel that the world is a threat. If we did,
we wouldn't so freely walk through it without apprehension. We don't feel like we
are being attacked by the world, at all.

Both of the above imply that sociopathy can come and go - either when the causal event has
subsided or when we no longer feel threatened. Sociopathy is a result; a fixed state. It can't
be turned on and off, not even when with someone with whom we have a bond.

Many people are misdiagnosed as sociopaths because they do shit like go on killing sprees.
Society really needs to understand that some people just do crazy shit without a mental
disorder. Some people are desensitised to certain things and therefore do not see anything
wrong with doing it. Some people just don't like the world. All these people have sociopathic
traits, but that doesn't actually make them sociopaths. Technically, everyone has and
expresses sociopathic traits to varying degrees, but that doesn't make them a sociopath at
all.

Regarding my theory on the empathy situation. I saw something and it must have been
during one of my slower moments because it was the only way I was able to realise what was
actually happening in my head. I was watching either a TV show or movie - I can't
remember exactly because I watch so much shit in a day - that was showing scenes of war. I
wasn't initially looking at the screen during this particular scene, so when I looked up, it
caught me by surprise. There were children laying dead on the floor. It was enough to make
non-ASPD individuals cry or, at least, feel a deep sense of sorrow. For me, however, I saw it
differently. Body, body, dust, broken buildings. After a couple seconds, I thought to myself
"this is sad". It was only then that it dawned upon me what exactly happens - I see the
objects, I see the event and then I see the actual situation at hand. It was all processed in 3
distinct parts. Most people see the situation first and then see the objects and the event. I
can only speculate that the order in which one processes these things is what determines the
ability to have an empathetic response, but it all usually happens too fast to notice. It was an
interesting moment, I must admit.

Now, as for why we can feel empathy for TV characters more than real people (and I know it
isn't just me because I laughed about this with another sociopath who thought it was just
him). The way I see it, we know TV characters are part of a fantasy land. It's not real, so we
don't need to apply the same rules as we do to the real world. There's no harm that can come
from empathising with a TV character because it has no bearing on actual life, so there's no
chance of it hindering us. It's one of the few experiences in life where we are able to get lost
in another world without worry. This can probably hold true for books, too, but I can't
testify to that because you wouldn't catch me reading a novel for love nor money.

Sociopaths in love. This, for some reason, is such a hot topic, so I'll explain it. Yes, we can
love. It can be deep, obsessive and with a singular-focus on the one person. We are
possessive. We are territorial. However, this only happens with people we bond with. We
don't (intentionally) hurt people if a bond exists, so when the bond is there, the relationship
can be just as awesome as a relationship with a normal person. So, why are sociopaths
known for destructive relationships? Simple - because many (especially LFSs) get into a
relationship just for sex or to have someone there, for whatever reason. There's no bond
created, so it's essentially just two people fucking and whatever else. Again, we see this in
everyday life with most types of people. Obviously, with no bond, a sociopath doesn't give a
shit about you, and you are just another object to them, so it's to be expected. The
preconceived notion that a sociopath can never and will never love a person is idiotic, at
best, and go-cremate-yourself stupid, at worst. If you are in a relationship with a sociopath
and they are actively being sociopathic towards you, leave. They don't love you; probably
never will; don't waste any more of your time. If they threaten to kill themselves, just laugh
(to yourself, at least). No sociopath is going to commit suicide over that trivial shit. If they
threaten to kill you, laugh harder (again, to yourself). They'll want to, but it's a lot of hassle,
so unless you are in a perfect situation that will allow the murder to go unnoticed, the
chances are slim. Unless you have done something that they see as betrayal, there's an
almost certain chance they are bluffing. If you are dealing with a low-functioning sociopath,
just inform the police or people like family members and employers immediately, in case
they try any of that “destroy your life” shit. If you are dealing with a high functioning one,
we won't go out of our way for you. If you stay and hope any sociopath will change, then you
likely deserve whatever it is they do to you. Stupidity receives no sympathy.

We aren't very different from normal people, but we're more capable of acting on the
thoughts and wants of normal people than they are because we don't have the general
morals and ethics of society restraining us.

So, what exactly is the definition of Sociopathy? One big trust issue and a giant fuck
you.

Have a nice day.