abstract: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 are only found in the Irish orthography where many of them can be analysed as a tetragraph plus the vowels e or i on either side to indicate that the neighboring consonants are palatalized "slender".