Trigraph (orthography)

A trigraph is a sequence of three letters that together represent a single phoneme (sound) or a digraph representing a single phoneme where that digraph then participates in another digraph or is modified in some other way by a third adjacent letter. In essence, it functions as a single unit of sound in a written language. The individual letters, when considered separately, do not have the same phonetic value as the trigraph as a whole. Trigraphs are common in languages like German, Italian, Spanish, Welsh, and Dutch, among others, although their frequency and specific sound values vary considerably by language. Recognizing trigraphs is an important aspect of literacy because failing to identify them can lead to mispronunciation and misunderstanding of written words. The distinction between a trigraph and simply three adjacent letters that each represent a separate sound is crucial. The defining feature is the unitary phonetic value associated with the entire three-letter sequence.