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cluster

/ˈklʌstər//ˈklʌstə/·noun, verb
a close-packed group; to gather into a tight, dense bunch
Fig. 1 — I watch grapes drift in from every side toward a bare stem and settle against one another, closer and closer, until they hang as one tight bunch with no space left between.
01Definition

A cluster is a group of things packed closely together — a cluster of grapes, of stars, of houses — and to cluster is for them to gather into such a tight bunch. From the Old English clyster, an old word for a bunch or branch of things growing together, a bunch of grapes being the classic image. What defines a cluster is not a boundary but density: the members crowd near one another, closer than to anything outside. The word stretches from the spatial (stars cluster) to the temporal (a cluster of events) and the technical (a cluster of data points).

02In use
  • iThe houses cluster around the old church, then thin out toward the fields.
  • iiA dense cluster of stars marks the heart of the galaxy.
  • iiiReported cases began to cluster in three neighbouring towns.
03Collocations
  • a cluster of
  • cluster around
  • cluster together
  • cluster analysis
  • cluster headache

Family clustered (adjective) · clustering (noun)

04Relations

=bunch, gather, group, huddle, congregate

≠scatter, disperse, spread

05Compared
PairThe difference
cluster vs assemblefit parts together in order, or gather for a purpose → assemble; crowd things into a tight, dense bunch by nearness → cluster.
cluster vs combinethings packing into a tight, dense group while staying separate → cluster; separate things joined together into one set → combine.
cluster vs come togethercrowd many things into a tight, dense bunch by nearness → cluster; separate people or things unite into one, often in shared effort → come together.
cluster vs congregatepack things or people into a tight, dense bunch by nearness → cluster; people come together in a crowd of their own accord → congregate.
cluster vs consolidategather into a tight, dense bunch where the parts stay distinct → cluster; combine scattered things into one stronger, firmer whole → consolidate.

Also compared with disband, disperse, dissipate, dissolve, gather, integrate, join, scatter, unite

06TOEFL & IELTS

The academic gold is 'a cluster of' + a plural noun — a cluster of islands, of cases, of studies — a pattern you can lift straight into writing. Mind the technical senses: in statistics, cluster analysis groups data points by similarity; a 'cluster headache' is named for attacks grouped in time, not space. Cluster is both noun and verb of the same form, and differs from a plain group by its defining closeness.

07Asked
Is 'cluster' a noun or a verb?
Both, with the same form. As a noun it is the close-packed bunch itself (a cluster of grapes); as a verb it means to gather into such a bunch (the houses cluster on the hill). The word comes from Old English clyster, an old term for a bunch of things growing together — a bunch of grapes is the classic image, exactly the tight knot the grapes form in the scene above.
What does 'a cluster of' mean?
It is the core pattern: 'a cluster of' + a plural noun, meaning a number of them grouped close together — a cluster of islands, a cluster of stars, a cluster of errors. It travels well into academic writing: a cluster of studies, a cluster of symptoms, a cluster of cases all read naturally and precisely.
Why is it called a 'cluster headache'?
Because the attacks come grouped in time, not in space: they strike in bouts or 'clusters' — often at the same hour each day for weeks — then ease for months. It is a good example of cluster's temporal sense (a cluster of events close together on the calendar), extending the usual spatial 'bunch'.
What does 'cluster' mean in statistics or computing?
In statistics and data science, a cluster is a set of data points more similar to each other than to points outside it, and cluster analysis is the method that discovers such groups rather than defining them in advance. In computing, a 'cluster' is a set of linked machines that work together as one system.
What is the difference between a cluster and a group?
A cluster is a group whose members are close together — tight proximity or density is the defining feature. A plain group needs no such closeness; its members can be scattered and still count as a group. So every cluster is a group, but only a dense, close-packed group earns the word cluster.
How do you pronounce cluster?
KLUH-stuh (/ˈklʌstər/) — one stressed syllable then a light one, the u a short 'uh' as in 'bus'. American English sounds the final r; British English softens it to a schwa. Fittingly, the word even opens with a consonant cluster of its own — the /kl/ that so many learners find tricky.