Here's how it goes, AFAIK : million, billion, trillion, quadrillion, quintillion, sextillion, septillion, octillion, nonillion, decillion. This sequence uses the Latin roots for numbers, not the Greek roots (tetra-, penta-, hexa-, hepta-).
Speaking a Latin language can be handy once in a very great while.
And 'milliard' is actually a French term which was borrowed by British English.
[ July 26, 2003, 14:08: Message edited by: Erax ]