the number that is represented as a one followed by 6 zeros (in Roman numerals, M written with a macron over it) denoting a quantity consisting of 1,000,000 items or units
If you talk about millions of people or things, you mean that there is a very large number of them but you do not know or do not want to say exactly how many. The programme was viewed on television in millions of homes
The plural form is million after a number, or after a word or expression referring to a number, such as `several' or `a few'