(astronomy) a densely-packed spherical star cluster containing thousands to millions of stars

(astronomy) A group of gravitationally bound stars and other material (such as nebulae and planets), conventionally with one generation of similarly aged stars from the same pre-stellar nebula.

(pathology) An extremely painful, cyclical and unilateral headache.

(artificial intelligence, statistics) The classification of objects into different groups, or more precisely, the partitioning of a data set into subsets (clusters), so that the data in each subset (ideally) share some common trait - often proximity according to some defined distance measure.

(physics) Any of a subset of graph states that can be fitted to a regular cubic lattice

plural of cluster bomb

plural of cluster headache

plural of cluster analysis

plural of cluster fuck

plural of open cluster