A group of similar things or people positioned or occurring closely together. The astronomer observed a cluster of stars through the telescope.
A group of data points in a data set that are close to each other according to some distance measure. The data analyst identified a cluster of high-value customers in the dataset.
A group of consonants pronounced in immediate succession, as in the word 'splint'. The word 'spring' contains a consonant cluster at the beginning.
A number of similar things growing or grouped closely together; a bunch. She picked a cluster of grapes from the vine.
A set of interconnected computers that work together as a single system. The company migrated its services to a high-availability server cluster.