Empathy

According to the Merriam-Webster dictionary, empathy is a noun that comes from "the Greek empatheia, which means passion, and the word empathes, which means emotional. Around 1850 it gained its modern definition, which is "the imaginative projection of a subjective state into an object so that the object appears to be infused with it" or, the more common definition, "the action of understanding, being aware of, being sensitive to, and vicariously experiencing the feelings, thoughts, and experience of another of either the past or present without having the feelings, thoughts, and experience fully communicated in an objectively explicit manner; also : the capacity for this". http://www.merriam-webster.com/dictionary/empathy

Encyclopedia Britanica has a slightly different definition, but it sounds a bit more like the normal definition: "the ability to imagine oneself in another’s place and understand the other’s feelings, desires, ideas, and actions. It is a term coined in the early 20th century, equivalent to the German Einfühlung and modeled on 'sympathy.' " http://www.britannica.com/EBchecked/topic/186011/empathy

Basically, it is the ability for a person to feel what someone else feels without necessarily experiencing what they have. What I find interesting is that both sides have a different origin for the word even though both are rather credible sources.