billion

Etymology

From French billion, from bi- (“two”) + -illion.

num

1. (US, modern British & Australian, short scale) a thousand million (logic: 1,000 × 1,000^(2): 1 followed by nine zeros, 109); a milliard
   At the last assessment it [the national debt] amounts to seven billion pounds (£7,000,000,000). 1921-01-24, “National Finances”, in Devon and Exeter Gazette, page 5
   In America alone, people spent $170 billion on “direct marketing”—junk mail of both the physical and electronic varieties—last year. Yet of those who received unsolicited adverts through the post, only 3% bought anything as a result. 2013-05-25, “No hiding place”, in The Economist, volume 407, number 8837, page 74
   However, despite the prospect of HS2 being curtailed and the revelation that the programme is late and billions over budget, for now, at least, work on the scheme appears to be business as usual 2019 October, Dan Harvey, “HS2 costs rise as schedule slips”, in Modern Railways, page 9
2. (dated, British & Australian, long scale) A million million (logic: 1,000,000^(2): a 1 followed by twelve zeros; 1012)
   n = 1,000,000,000,000, that is, = a billion, or the square of a million 1778, Francis Maseres, “A Method of Finding, by the Help of Sir Isaac Newton's Binomial Theorem, a Near Value of the very Slowly Converging Infinite Series …”, in Philosophical Transactions of the Royal Society, volume lxviii, number xli
   There is a bill to be picked up for cleaning the former Soviet countries of £1 billion. By that I mean a British billion, because when I was little I was told that a billion was a million million and then the Americans said that it was a thousand million. Well, I am talking about a million million pounds worth of clean-up to be done. 2000-11-08, Stephen Ladyman, “[Speech to the House of Commons]”, in Hansard
3. (colloquial, hyperbolic) An unspecified very large number.
   There were billions of people at the concert.