Consonant cluster

In linguistics, a consonant cluster, consonant sequence or consonant compound is a group of consonants which have no intervening vowel. In English, for example, the groups /spl/ and /ts/ are consonant clusters in the word splits.

Some linguists argue that the term can only be properly applied to those consonant clusters that occur within one syllable. Others contend that the concept is more useful when it includes consonant sequences across syllable boundaries. According to the former definition, the longest consonant clusters in the word extra would be /ks/ and /tr/, whereas the latter allows /kstr/ or /kstʃr/ in some dialects.

Languages' phonotactics differ as to what consonant clusters they permit.

Many languages are more restrictive than English in terms of consonant clusters. Many languages forbid consonant clusters entirely. Hawaiian, like most Malayo-Polynesian languages, is of this sort. Japanese is almost as strict, but allows a sequence of a nasal or approximant, plus another consonant, as in Honshū [hoɴɕuː] (the name of the largest island of Japan), and Tokyo [toːkjoː]. Standard Arabic forbids initial consonant clusters and more than two consecutive consonants in other positions. So do most other Semitic languages, although Modern Israeli Hebrew permits initial two-consonant clusters (e.g. pkak "cap"; dlaat "pumpkin"), and Moroccan Arabic, under Berber influence, allows strings of several consonants. Like most Mon–Khmer languages, Khmer permits only initial consonant clusters with up to three consonants in a row per syllable. Finnish has initial consonant clusters natively only on South-Western dialects and on foreign loans, and only clusters of three inside the word are allowed. Most spoken languages and dialects, however, are more permissive. In Burmese, consonant clusters of only up to three consonants (the initial and two medials—two written forms of /-j-/, /-w-/) at the initial onset are allowed in writing and only two (the initial and one medial) are pronounced. These clusters are restricted to certain letters. Some Burmese dialects allow for clusters of up to four consonants (with the addition of the /-l-/ medial, which can combine with the above-mentioned medials.

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