1680s, from Fr. billion (originally byllion in Chuquet's unpublished "Le Triparty en la Science des Nombres", 1484; copied by De la Roche, 1520), from bi- "two" + (m)illion. A million million in Britain and Germany (numeration by groups of sixes), which was the original sense; subsequently altered in Fr. to "a thousand million" (numeration by groups of threes) and picked up in that form in U.S., "due in part to French influence after the Revolutionary War." France then reverted to the original meaning in 1948. British usage is truer to the etymology, but U.S. sense is increasingly common there in technical writing.