The word fraudulent is an adjective that refers to engaging in some activity that is deceitful or constitutes fraud. It refers to something as being gained, characterized or constituting fraud. The word comes from the Middle English and was taken from the Old French having been derived from the Latin word fraudulentus. Synonyms of fraudulent are fallacious and deceitful, it can be defined as something false and deceptive and its opposite is something that is genuine, real, valid, authentic and fair. People who commit fraud or indulge in fraudulent behaviour are known as fraudsters and there have been quiet a few famous fraudsters including Frank Abagnale Jr on whom the Hollywood movie "Catch Me If You Can" was based. Others include Alves Reis who forged banknotes to the tune of a hundred and fifty million USD.