Trigraph (orthography)
A trigraph (from Ancient Greek τρεῖς (treîs) 'three' and γράφω (gráphō) 'to write') is a group of three characters used to represent a single sound or a combination of sounds that does not correspond to the written letters combined. == Latin-script trigraphs == For example, in the word schilling, the trigraph sch represents the voiceless postalveolar fricative /ʃ/, rather than the consonant cluster /sx/.