What are Consonant Clusters in English Grammar?

Sound groupings that come before, after, and between vowels

Consonant clusters
The letters in italics represent consonant clusters. Edgardo Contreras / Getty Images

In linguistics, a consonant cluster (CC)—also known simply as a cluster—is a group of two or more consonant sounds that come before (onset), after (coda) or between (medial) vowels. Onset consonant clusters may occur in two or three initial consonants, in which three are referred to as CCC, while coda consonant clusters can occur in two- to four-consonant groups.

Common Consonant Clusters

In "The Routledge Dictionary of English Language Studies," author Michael Pearce explains that the written English language contains up to 46 permissible two-item initial consonant clusters, ranging from the common "st" to the less common "sq," but only nine permissible three-item consonant clusters.

Pearce illustrates the common three-item initial consonant clusters in the following words: "spl/ split, /spr/ sprig, /spj/ spume, /str/ strip, /stj/ stew, /skl/ sclerotic, /skr/ screen, /skw/ squad, /skj/ skua," wherein every word must start with an "s" and be followed by a voiceless stop, such as "p" or "t" and a liquid or glide like "l" or "w." 

Consonant Cluster Reductions

Consonant clusters occur naturally in written and spoken English, although sometimes, they may be altered. Codas, the consonant clusters that end words, may contain up to four items, however, they are often truncated in connected speech if the consonant cluster is too long (as in the word glimpsed being acceptably written as glimst.)

This process, called consonant cluster simplification (or reduction) sometimes occurs when at least one consonant in a sequence of adjacent consonants is elided or dropped. In everyday speech, for instance, the phrase "best boy" may be pronounced "bes' boy," and "first time" may be pronounced "firs' time."

In spoken English and rhetoric, consonant clusters are often truncated naturally to increase speed or eloquence of speech. We generally drop a repeated consonant if it occurs at the end of one word and again at the beginning of the next. The process of consonant cluster reduction has no set rules, however, it is confined by certain linguistic factors that inhibit the operation of reducing such words.

Walt Wolfram, a sociolinguist at North Carolina State University, explains that "with respect to the phonological environment that follows the cluster, the likelihood of reduction is increased when the cluster is followed by a word beginning with a consonant." What this means for average English users is that cluster reduction is more common in phrases like "west coast or cold cuts" than in "west end or cold apple."

Consonant Cluster Reduction in Poetry and Rap

As described by Lisa Green in "African American English: A Linguistic Introduction," consonant cluster reduction is often a tool used in poetry to force similar-sounding words with different consonant endings to rhyme. She notes the technique is extremely common in poetic raps of African American origin in the United States.

Take for example the words test and desk: While they don't form a perfect rhyme in their original form, by using consonant cluster reduction, the rhyme "Sittin’ at my des’, takin’ my tes’" can be forced through truncation.


  • Pearce, Michael. The Routledge Dictionary of English Language Studies. Routledge. 2007
  • Wolfram, Walt. "Dialect in Society" chapter seven in "The Handbook of Sociolinguistics." Blackwell Publishing Ltd.1997; John Wiley. 2017
  • Green, Lisa J. "African American English: A Linguistic Introduction." Cambridge University Press. 2002
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Nordquist, Richard. "What are Consonant Clusters in English Grammar?" ThoughtCo, Apr. 5, 2023, thoughtco.com/what-is-consonant-cluster-cc-1689791. Nordquist, Richard. (2023, April 5). What are Consonant Clusters in English Grammar? Retrieved from https://www.thoughtco.com/what-is-consonant-cluster-cc-1689791 Nordquist, Richard. "What are Consonant Clusters in English Grammar?" ThoughtCo. https://www.thoughtco.com/what-is-consonant-cluster-cc-1689791 (accessed May 30, 2023).