milliardaire
/ˌmɪlɪəˈdɛː/Now rare
noun
A person possessing a thousand million pounds (dollars, etc.); an immensely wealthy person.
Origin
Late 19th century; earliest use found in Francis Edgeworth (1845–1926), economist and statistician. From milliard + -aire, in quot. 1897 after Dutch milliardair, itself probably after French milliardaire.