An asymmetric type of collection of stars that shared a common origin.

An open star cluster. Term no longer used since easy to confuse with clusters of galaxies. Originally named galactic clusters since these objects are often confined to the plane of the Milky Way Galaxy.

a self-gravitating cluster of stars, typically created from the same planetary nebula, within a galaxy

Another term for open cluster as they are typically located in the arms of spiral galaxies where there is abundant dust and gas essential for star formation.

An "open" cluster of stars located in the spiral arms or disk of the Galaxy.

a loose cluster of a small number of stars; aka open cluster

This is an alternative name for an open star cluster in our Galaxy. It indicates that the cluster lies within our Galaxy rather than in the halo round our Galaxy, where globular clusters lie.