a consonant cluster (or consonant blend) 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/,[1] whereas the latter allows /kstr/. The German word Angstschweiß (/aŋstʃvaɪs/; "fear sweat") is another good
example, with a cluster of five consonants: /
ŋstʃv/. The Dutch word angstschreeuw (/ ɑŋstsχrɪːw/; "scream of fear") has an even
longer cluster, with six consonants: /ŋstsχr/.