Astronomy. A feature, system, etc., resembling the Milky Way; (in later use) spec. any of the numerous systems, often of millions or billions of…

With plural. A hypothetical or imagined cosmos with particular distinguishing properties; each of a number of possible all-encompassing entities or…

Astronomy. A body of stars bound together by gravitational attraction. In later use also: a planetary system.

a distinct stellar system, such as that to which the sun belongs, occupying a detached position in space.

Astronomy. Originally: an indistinct cloud-like, luminous object seen in the night sky, such as a cluster of distant stars, a galaxy, or a cloud of…

Astronomy. A supergiant galaxy (see sense B. 2b).