In lay terms, being Empathic means being able to feel what another person is feeling, either emotionally, physically, or both (receiving emotional or sensory information through non-physical or "extra-sensory" means).
A true Empath can sense or experience the emotions and/or physical sensations of others, both in close proximity, and/or at a distance.
Advanced Empaths also sometimes have the ability to ‘draw out’ physical or emotional pain from another person and take it into their own body, with the intention of then releasing or expelling that pain and providing temporary or permanent relief for the subject.
An Empath is often highly aware of the health and state of mind of their loved ones, no mater how physically near or far away the individuals may be. It is not uncommon for an Empath to ‘freak out’ for no reason, only to discover later that a friend or family member went through some sort of trauma at that exact moment. This is particularly noticeable in twins or other Empaths who spend a great deal of time together, as they will often physically experience the same traumas as their loved ones.
For example, one girl suddenly experienced a severe asthma attack and nearly died in the middle of a supermarket, only to find out later that her twin sister had accidentally inhaled battery acid and was being treated at a nearby hospital. The accident and the asthma attack happened almost simultaneously, in different parts of the city.
Similarly, many Empaths experience a constant barrage of unexplainable aches, pains, and mood swings, not realizing that they are experiencing the physical and emotional states of their friends and loved ones.
Sadly, many are misdiagnosed as suffering from chronic fatigue syndrome, fibromyalgia, bi-polar or other mood/personality disorders, schizophrenia, or even hypochondria.
For a detailed treatise on this subject, please read the article "Feeling a Little Empathic - A Survival guide for the Extraordinarily Sensitive" by David M. Burgess, available for free online, or for purchase in booklet form through CafePress.