Why is the ninth month called September?
late 14c., from Old French million (late 13c.), from Italian millione (now milione), literally "a great thousand," augmentative of mille "thousand," from Latin mille, which is of uncertain origin. Used mainly by mathematicians until 16c. India, with its love of large numbers, had names before 3c. for numbers well beyond a billion. The ancient Greeks had no name for a number greater than ten thousand, the Romans for none higher than a hundred thousand. "A million" in Latin would have been decies centena milia, literally "ten hundred thousand." Million to one as a type of "long odds" is attested from 1761. Related: Millions.