What does digraph mean?
A digraph is a combination of exactly two letters that work together to represent a single sound, even though neither letter alone carries that value. Familiar examples include 'sh' in 'ship', 'ch' in 'chat', 'th' in 'think', and 'ea' in 'bread'. The term belongs chiefly to linguistics and phonics teaching, where understanding digraphs helps learners connect spelling to pronunciation — a real challenge in English, where many sounds have several possible spellings. Digraphs are usually classified as vowel digraphs ('oo' in 'moon') or consonant digraphs ('ph' in 'phone'). Separately, in mathematics and computer science, a digraph is short for 'directed graph': a set of nodes joined by arrows that point in a particular direction, used to model things like web links or road networks. Despite the shared spelling, these are distinct technical senses drawn from the same Greek roots meaning 'two' and 'writing'.
A pair of letters representing a single speech sound, as 'sh' in 'ship'.
"The word 'chair' begins with the consonant digraph 'ch'."
Distinguished from a blend, where both letters retain their own sounds.
(Mathematics and computer science) Short for directed graph: a graph whose edges each carry a direction.
"Page-ranking algorithms operate on a digraph whose vertices are web pages."
Regular plural; used when referring to multiple letter-pairs or multiple directed graphs.
"English has more vowel digraphs than most learners expect."
'Ship', 'each', and 'phone' all hide a secret: pairs of letters secretly working together as a single team called a digraph.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of digraph
Digraph comes from the Greek elements di- ('twice, double') and -graph ('something written'), ultimately from graphein, 'to write'. It entered English in the early 19th century as part of the vocabulary of modern linguistics, alongside related coinages such as trigraph. Its Greek root also gives English words like diagram, graphic, and calligraphy. The computing sense arose later in the 20th century by analogy with the mathematical term graph.
Related word forms
How digraph is actually used
In everyday use, 'digraph' appears mainly in linguistics, literacy education, and phonics instruction; it is a technical term rather than casual vocabulary. The computing sense is common in academic writing about graphs and networks. Some linguists distinguish a true digraph (one sound) from letter sequences that merely occur together.
Easily confused with digraph
A digraph is a written pair of letters representing one sound, whereas a diphthong is a single vowel sound that glides from one quality to another within a syllable.
A digraph consists of two letters representing one sound, while a trigraph uses three letters for a single sound, as in 'tch' in 'catch'.