While I had been aware of the different meaning of the term billion in English and German, recent discussions by users in a German-speaking online forum led me to look up the details. As is often the case, the full story is even more interesting, even if your fortune is nowhere near such numbers.
Let’s start with the term million, for which no confusion arises. It is a shorthand to denote 1000 times 1000 or, using powers, 106 units of something (people, currency, cars, …). Clearly, it is useful to have another shorthand for 1000 millions. However, this is where things become tricky. Whereas many languages adopted the French word milliard (Milliarde in German) for this purpose, the term billion (certainly easier to pronounce) became more popular in English. In particular, a billionaire in English is a Milliardär in German. However, billion was historically used with two different meanings (referred to as short scale and long scale), meaning either 109 (1000 millions) or 1012 (1 million millions). This goes back to a change of the definition by the French, see Wikipedia. In contrast, in most European languages, billion (Billion in German) refers exclusively to 1012 (1 million millions, or 1000 milliards). Since billion is reserved for 109 in English, another term (trillion) is needed for 1012 (Billion in German).
Regarding the origin of the word billion, let me quote Wikipedia:
According to the Oxford English Dictionary, the word billion was formed in the 16th century (from million and the prefix bi-, “two”), meaning the second power of a million (1,000,0002 = 1012).
While the two different definitions rarely cause confusion today in English, problems arise when translating to other languages. In principle, the rules are simple:
- million in English = Million in German
- billion in English = Milliarde in German
- trillion in English = Billiarde in German
However, there is quite some confusion among both professionals (in particular journalists) and amateurs. For example, I today saw journalists translate the liabilities of a company from $17 billion (original English article) first to $17 milliards and then to €17 millions, which would be only 1/1000 of the original amount. In fact, quite a few people seem to be under the incorrect impression that a billion US dollars has to be divided by 1000, whereas a billion Euros remains the same. This is of course nonsense: the necessary conversion is entirely due to different languages and has nothing to do with currencies.