Milky-way

noun, Astronomy.
1.
the spiral galaxy containing our solar system. With the naked eye it is observed as a faint luminous band stretching across the heavens, composed of approximately a trillion stars, most of which are too distant to be seen individually.
noun the Milky Way
1.
the diffuse band of light stretching across the night sky that consists of millions of faint stars, nebulae, etc, within our Galaxy
2.
another name for the Galaxy
n.

late 14c., loan-translation of Latin via lactea. See also galaxy.
Milky Way
(mĭl’kē)
The spiral galaxy that contains our solar system. Made up of an estimated two hundred billion stars or more, it is seen from Earth as an irregular band of hazy light across the night sky. The solar system is located in one of the revolving spiral arms, about 50 light-years north of the galactic plane and some 27,700 light-years from the galaxy’s center, which lies in the direction of the constellation Sagittarius. It takes approximately 250 million years for the solar system to orbit the galactic center, which is believed to contain a massive black hole. The Milky Way measures about 100,000 light-years in diameter and is the second largest galaxy, after the Andromeda Galaxy, in the cluster known as the Local Group. See also spiral galaxy.

The galaxy to which our sun belongs.

Note: The Milky Way is also the swath of light in the night sky produced by the other stars in the galaxy.