Meaning

noun the number that is represented as a one followed by 6 zeros

noun a very large indefinite number (usually hyperbole)

adjective (in Roman numerals, M written with a macron over it) denoting a quantity consisting of 1,000,000 items or units

originInherited from Middle English milioun, from Middle French milion, from Old French millon, from Italian milione (“million”, from mille (“thousand”, from Latin mille) + -one). Compare -illion.

Etymology from Wiktionary, CC BY-SA 3.0