A psychological condition, otherwise known as pathological or compulsive lying, in which the sufferer habitually lies. The lies are caused by an internal need to lie, not environmental or social factors. Unlike in psychotic or delusional disorders, people with this condition can recognize they are lying, though they may be unwilling to do it, leading to anger, confusion, and (in some cases) violence following confrontation.
My friend has a terrible case of pseudologia fantastica. She says she's had ten different kinds of cancers, but she's never even been inside a hospital.