Multigraphs (orthography)

pair of characters used to write one phoneme

group of three characters used to represent a single sound or a combination of sounds that does not correspond to the written letters combined

A tetragraph, , is a sequence of four letters used to represent a single sound (phoneme), or a combination of sounds, that do not necessarily correspond to the individual values of the letters. In German, for example, the tetragraph tsch represents the sound of the English digraph ch. English does not have tetragraphs in native words (the closest is perhaps the sequence -ough in words like through), but chth and phth are true tetragraphs when found initially in words of Greek origin such as chthonic and phthisis.

sequence of letters that behaves as a unit, not as a sequence of parts

A pentagraph (from the , pénte, "five" and γράφω, gráphō, "write") is a sequence of five letters used to represent a single sound (phoneme), or a combination of sounds, that do not correspond to the individual values of the letters. In German, for example, the pentagraph tzsch represents the sound of the English digraph ch, and indeed is found in the English word Nietzschean. Irish has several pentagraphs.

A hexagraph (from the , héx, "six" and γράφω, gráphō, "write") is a sequence of six letters used to represent a single sound (phoneme), or a combination of sounds that do not correspond to the individual values of the letters. They occur in Irish orthography, and many of them can be analysed as a tetragraph followed by the vowels or on either side to indicate that the neighbouring consonants are palatalized ("slender"). However, not all Irish hexagraphs are analysable that way. The hexagraph , for example, represents the same sound (approximately the vowel in English "write") as the trigraph a