Webster's Revised Unabridged Dictionary · 1913

Billion

Billion ({not transcribed}) , noun

[French billion, arbitrarily formed from Latin bis twice, in imitation of million a million. See Million.]

According to the French and American method of numeration, a thousand millions, or 1,000,000,000; according to the English method, a million millions, or 1,000,000,000,000. See Numeration.