trigraph (orthography)

A trigraph (from the Greek words treis = three and graphein = write) is a group of three letters used to represent a single sound or a combination of sounds that does not correspond to the written letters combined. For example, in the word schilling, the trigraph "sch" represents the voiceless post-alveolar fricative (IPA: /ʃ/). In the word "night", "igh" represents the vowel (IPA: ) (a diphthong). Other examples are "beautiful" (eau), "adieu" (ieu).
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