A faint band of light crossing the night sky, made up of vast numbers of faint stars forming the bulk of the galaxy of which our solar system is a part.
Definition of Milky Way in US English:
Milky Way
proper nounˈˌmɪlki ˈweɪˈˌmilkē ˈwā
1A faint band of light crossing the sky, made up of vast numbers of faint stars. It corresponds to the plane of our Galaxy, in which most of its stars are located.