What does cluster mean?
A cluster is a group of similar things or people positioned closely together, whether a knot of spectators, a bunch of grapes, a gathering of stars, or a set of neighboring data points. As a verb, to cluster means to collect or arrange in such a tight grouping, as when shops cluster around a train station. The word is neutral in tone and appears everywhere from everyday conversation to technical writing: statisticians perform cluster analysis, doctors speak of cluster headaches, linguists describe consonant clusters, and computer scientists build server clusters. Its strength lies in suggesting both similarity and proximity — the grouped items belong together and sit near one another. Derived forms include clustered and clustering, and fixed phrases such as cluster bomb and cluster of grapes show how deeply embedded the word is across registers and disciplines.
A group of similar things or people positioned or occurring closely together; also, a bunch of flowers or fruit on a single stem.
"A cluster of cottages nestled at the foot of the hill."
Commonly used with the preposition 'of': a cluster of stars, a cluster of cases.
To gather or cause to gather into a close group or bunch.
"Mushrooms clustered around the base of the old oak."
Regular plural; used when referring to multiple distinct groupings.
"Several clusters of wildflowers dotted the meadow."
The stars in the Pleiades, the servers in a data center, and the letters 'str' in 'string' are all clusters — one word quietly ties astronomy to computing to linguistics.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cluster
Cluster first appeared in English in the early 17th century, though its exact origins are uncertain. It is generally thought to derive from Old English 'clyster', meaning a mass or lump, which itself may relate to 'clot' — all pointing to a Germanic root conveying the idea of a thickened, congealed mass. The sense evolved from a physical lump toward any close grouping of things, and the verb followed naturally from the noun.
Related word forms
How cluster is actually used
Neutral in register and suitable for both formal scientific writing and everyday speech. In technical fields — statistics, computing, linguistics, medicine — it carries precise specialized meanings, so context usually signals which sense applies.
Easily confused with cluster
Clutter is a disorderly mess of things, while a cluster is simply a tight grouping that need not be untidy.