mythomania

We wouldn't lie to you about the history of mythomania. It comes, via the French mythomanie, from two ancient roots: the Greek mŷthos (meaning "myth") and the Late Latin mania (meaning "insanity marked by uncontrolled emotion or excitement"). One myth about mythomania is that it's a very old word; actually, the earliest known uses of the term date only from the beginning of the 20th century. It was predated by a related word, mythomaniac, which appeared around the middle of the 19th century. Mythomaniac referred to someone who was obsessed with or passionate about myths before it was applied to individuals affected with or exhibiting mythomania.