cluster

UK: /ˈklʌstə^r/ US: /ˈklʌstɚ/ ,(klus′tər)

WordReference Random House Learner's Dictionary of American English © 2026

clus•ter /ˈklʌstɚ/   n. [countable]

1. a number of things of the same kind, growing or held together;
   bunch:
   a cluster of flowers.
2. a group of persons or things close together:
   That cluster of stars is held together by gravitation.

v. 

3. to form or gather in a cluster: [no object]
   The students clustered around the professor.
   [~ + object]
   The students were clustered around the professor.

WordReference Random House Unabridged Dictionary of American English © 2026

clus•ter  (klus′tər), n. 

1. a number of things of the same kind, growing or held together;
   a bunch:
   a cluster of grapes.
2. a group of things or persons close together:
   There was a cluster of tourists at the gate.
3. Military [U.S. Army.] a small metal design placed on a ribbon representing an awarded medal to indicate that the same medal has been awarded again:
   oak-leaf cluster.
4. Phonetics a succession of two or more contiguous consonants in an utterance, as the str- cluster of strap.
5. Astronomy a group of neighboring stars, held together by mutual gravitation, that have essentially the same age and composition and thus supposedly a common origin. Cf. globular cluster, open cluster, stellar association.

v.t. 

6. to gather into a cluster or clusters.
7. to furnish or cover with clusters.

v.i. 

8. to form a cluster or clusters:
   The people clustered around to watch.

• bef. 900; Middle English; Old English cluster, clyster bunch; cognate with Low German kluster

clus′ter•ing•ly, adv. 
clus′ter•y, adj. 
Synonyms

• 8. group, gather, throng, crowd, bunch.

Collins Concise English Dictionary © HarperCollins Publishers::

cluster / ˈklʌstə/ noun

1. a number of things growing, fastened, or occurring close together
2. a number of persons or things grouped together

verb

1. to gather or be gathered in clusters

Etymology: Old English clyster; related to Low German Kluster; see clod, clot

ˈclustered adjective

ˈclustery adjective