Pathological lying, also known as mythomania and pseudologia fantastica, is the chronic behavior of compulsive or habitual lying. Unlike telling the occasional white lie to avoid hurting someone's feelings or getting in trouble, a pathological liar seems to lie for no apparent reason.

What do you call a person that exaggerates?

Exaggerator and overstater are both English words that fit your meaning.

What is an exaggeration of truth?

When you exaggerate you stretch the truth. ... After all, when you exaggerate, you're not really lying — you're just overstating things. The word exaggerate can also suggest that a particular characteristic is overdone or almost larger than life.