Definition - A branch of phonology that deals with restrictions that particular languages place on what are permissible combinations of phonemes, e.g. consonant clusters and vowel sequences.

Example -
English does not permit words that contain the consonant sequence tkbpqt, but it does permit the sequence cts as in facts.

Note: Superman-comic English permits the sequence Mxyzptlk (pronounced mĭks·yĕz′·pĭt·l·ĭk).

Etymology -
The word derives from the Greek phone, voice and taktikos, something which may be arranged or ordered.

Oxford English Dictionary -
Its first citation is from 1956:
"The key to our understanding of the syllable lies in the development of phonotactics, or the study of phonemic distribution."
(E. Haugen in M. Halle et al. For Roman Jakobson 216)

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