Neg, short for Negative entity.
That's a good question. Some may call it from the devil, some might call it negative energy. You might even call it an alien but in my experience I call it a person sending you the nasties.
A neg, as referred to in the contexts of AP, energy work or magic, are negative entities that cause you harm in some form, usually to your energy body, which then typically causes the manifestation of physical ailments.
Some negs can be seen as evil because they deliberately cause harm for no purpose other than to cause harm, such as a black magician who puts curses on people or enacts psychic attacks. Some are not really evil, no more than a leech or a scorpion could be called evil. Feeding off the energy of others is just what they do to survive, which is the case with some non-sentient lower astral life forms, or spirit entities like a succubus.
Hope this helps,
James.
May anyone say what the hell a "neg" is?
Grateful for answers
/jonas