million (n.)

"ten hundred thousand, a thousand thousands," late 14c., milioun, 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. From the start often used indefinitely for "a very great number or quantity."

In the West it was used mainly by mathematicians until 16c., but 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.

Definitions of million
million (n.)
the number that is represented as a one followed by 6 zeros;
Synonyms: " / one thousand thousand / meg
million (n.)
a very large indefinite number (usually hyperbole);
there were millions of flies
Synonyms: billion / trillion / zillion / jillion / gazillion / bazillion
million (adj.)
(in Roman numerals, M written with a macron over it) denoting a quantity consisting of 1,000,000 items or units;