quadrigraph

A quadrigraph is a sequence of four letters that represents a single sound or a combination of sounds. This linguistic unit is analogous to a digraph, which uses two letters, and a trigraph, which uses three. Quadrigraphs are less common than digraphs and trigraphs, but they do appear in various languages and in specific contexts.

In English, one common example of a quadrigraph is "ough," which can be pronounced in several different ways. For instance, in "though" it sounds like /oʊ/, in "tough" it sounds like /ʌf/, and in "through" it sounds like /uː/. Another example is "eigh," as seen in words like "eight" and "weigh," where it represents the /eɪ/ sound.

The concept of a quadrigraph extends beyond English. In other languages, different combinations of four letters might function similarly to represent particular phonemes or diphthongs. Understanding quadrigraphs is helpful in phonics instruction and in analyzing the orthography of a language. They highlight how written symbols can sometimes deviate from a simple one-to-one correspondence with spoken sounds, requiring learners to recognize these multi-letter units. The study of these grapheme-phoneme correspondences is a key aspect of literacy.