What is Digraph (orthography)?

A digraph, bigraph or digram is a pair of characters used to write one phoneme (distinct sound) or a sequence of phonemes that does not correspond to the two characters in sequence. The sound is often, but not necessarily, one which cannot be expressed using a single character in the orthography used by the language. Normally, the term "digraph" is reserved for graphemes whose pronunciation is always or nearly always the same.

When digraphs do not represent a special sound, they may be relics from an earlier period of the language when they did have a different pronunciation, or represent a distinction which is made only in certain dialects, like wh in English. They may also be used for purely etymological reasons, like rh in English.

In some languages, digraphs are considered individual letters, meaning that they have their own place in the alphabet, in the standard orthography, and cannot be separated into their constituent graphemes; e.g.: when sorting, abbreviating or hyphenating. In others, like English, this is not the case.

Some schemes of Romanization make extensive use of digraphs (e.g. Cyrillic to Roman for English readers), while others rely solely on diacritics (e.g. Cyrillic to the modified Roman used for Turkish). To avoid ambiguity, transliteration based on diacritics is generally preferred in academic circles. Many languages, like Serbian and Turkish, have no digraphs, and so transliterations into these languages also cannot use digraphs.

Types of digraphs

There are two main kinds of digraphs, sequences and double letters.

Sequences

This is a pair of different letters in a specific order. Examples in English are:

• ch usually corresponds to /tʃ/ (voiceless postalveolar affricate), to /k/ (voiceless velar plosive) when used as an etymological digraph in words of Greek origin, more rarely to /ʃ/ (voiceless postalveolar fricative)
• ck represents /k/ (voiceless velar plosive)
• gh represents /g/ (voiced velar plosive) at the beginning of words. Represents /f/ (voiceless labiodental fricative), or is silent at the end of words, and in compounds formed from such words.
• ng represents /ŋ/ (velar nasal)
• ph represents /f/ (voiceless labiodental fricative)
• qu usually represents /k^w/ or /k/; q is conventionally followed by u in native words.
• rh represents /ɹ/ (alveolar approximant), and is an etymological digraph found in words of Greek origin.
• sc normally represents /s/ (voiceless alveolar fricative) before e or i
• sh represents /ʃ/ (voiceless postalveolar fricative)
• th usually corresponds to /θ/ (voiceless interdental fricative) or /g/ (voiced interdental fricative). See also Pronunciation of English th.
• wh represents /ʍ/ (voiceless labial-velar fricative) in some conservative dialects; /w/ (voiced labial-velar approximant) in other dialects; and /h/ (voiceless glottal fricative) in a few words where it is followed by o, such as who and whole. See also Hwair and Phonological history of wh.
• wr represents /ɹ/ (alveolar approximant). Originally, it stood for a labialized sound, while r was a non-labialized rhotic, but this distinction was lost, and the two sounds have merged into a single phoneme, which is allophonically labialized at the start of syllables, as in red [ɹʷɛd].

Digraphs may also be composed of vowels. Common examples in English are:

• ea usually pronounced /i:/, /ɛ/ or /eɪ/.
• ie usually pronounced /i:/ or /aɪ/
• ai usually pronounced /ɛ/ or /eɪ/.
• ei usually pronounced /i:/, more rarely /aɪ/.
• au usually pronounced /ɔ/.
• eu usually pronounced /ju/.
• ou usually pronounced /aʊ/, more rarely /u:/.
• aw usually pronounced /ɔ/.
• ew usually pronounced /ju/.
• ow usually pronounced /oʊ/ or /aʊ/.

For further information on English, see English orthography.

In Dutch, the digraph ij, which often resembles a y (or a ÿ) in handwriting, represents the diphthong /ɛɪ/. Opinions are divided on whether it should be considered part of the alphabet.

Double letters

These are pairs of identical letters that have a special pronunciation. In some languages they indicate consonant length or vowel length, a stressed syllable or a new sound, but in other cases they are just part of the spelling convention. Ll is the most common in English, though it does not represent a different sound from l, being essentially an etymological digraph. In Welsh, however, it stands for a voiceless lateral, and in Spanish it stands for a palatal consonant. Ee and oo are common English digraphs made up of vowels. Some more examples:

• In several languages of western Europe, including English and French, ss is used between vowels for the voiceless sibilant /s/ (voiceless alveolar fricative), since an s alone between vowels is normally voiced, /z/ (voiced alveolar fricative). In German, an archaic version of this digraph originated the letter ß.
• In Romance languages such as Spanish or Italian, rr is used between vowels for the alveolar trill /r/, since an r alone between vowels represents an alveolar flap /ɾ/ (the two are different phonemes in these languages).
• In Italian, zz (as in the word pizza) is an affricate, /ts/ or /dz/.
• In several Germanic languages, including English, CC (where C stands for a given consonant) corresponds to C and signifies that the preceding vowel is short.

Ambiguity

Some letter pairs should not be interpreted as digraphs, but appear due to compounding, like in hogshead and cooperate. This is often not marked in any way (it is an exception which must simply be memorized), but some authors indicate it either by breaking up the digraph with a hyphen, as in hogs-head, co-operate, or with a diaeresis mark, as in coöperate, though this usage is rare in English.

In Czech also (and analogically in other Slavic languages), double letters may appear in compound words, but they are not considered digraphs. Examples: bezzubi (bez + zubi, toothless), cenni (cen + ni, valuable), černooki (černo + oki, black-eyed).

Digraphs versus letters

In some languages, digraphs and trigraphs are counted as distinct letters in themselves, and assigned to a specific place in the alphabet, separate from that of the sequence of characters which composes them, in orthography or collation. Other languages, such as English, make no such convention, and split digraphs into their constituent letters for collation purposes. Some language alphabets that include digraphs are:

• Croatian, Serbian. Note that in the Cyrillic orthography, these sounds are represented by single letters, rather than pairs of letters.
• lj corresponds to /ʎ/, (palatal lateral approximant)
• nj corresponds to /ɲ/ (palatal nasal)
• dž corresponds to /dʒ/ (voiced postalveolar affricate)
• Hungarian.
• cs represents /tʃ/ (voiceless postalveolar affricate)
• dz represents /dz/ (voiced postalveolar affricate)
• gy represents /ɟ/ (voiced palatal plosive)
• ly originally represented /ʎ/ (palatal lateral approximant), but in the modern language stands for /j/ (palatal approximant)
• ny represents /ɲ/ (palatal nasal)
• sz represents /s/ (voiceless alveolar fricative) (s is pronounced as /ʃ/)
• ty represents /c/ (voiceless palatal plosive)
• zs represents /ʒ/ (voiced postalveolar fricative)
• The Hungarian alphabet additionally contains a trigraph, dzs /dʒ/ (voiced postalveolar affricate).
• Polish.
• ch corresponds to /x/ (voiceless velar fricative)
• cz corresponds to /tʂ/ (voiceless retroflex affricate)
• dz corresponds to /dz/ (voiced alveolar affricate)
• dź corresponds to /dʑ/ (voiced alveolo-palatal affricate)
• dż corresponds to /dʐ/ (voiced retroflex affricate)
• rz corresponds to /ʐ/ (voiced retroflex fricative)
• sz corresponds to /ʂ/ (voiceless retroflex fricative)
• Scandinavian languages.
• aa represents /ɔ/, and is alternatively spelt å.
• Spanish. The following digraphs are considered part of the alphabet. They used to be sorted as separate letters, but a reform in 1994 by the Spanish Royal Academy has allowed that they be split into their constituent letters for collation. Note: the digraph rr has never been included in the Spanish alphabet, in spite of having a distinct pronunciation (alveolar trill).
• ch represents /tʃ/ (voiceless postalveolar affricate)
• ll corresponds to /ʎ/ (traditionally a palatal lateral approximant, though it has several dialectal variants in modern Spanish)
• Welsh. The digraphs listed below represent distinct phonemes. On the other hand, the digraphs mh, nh, and the trigraph ngh, which stand for voiceless consonants, but only occur at the beginning of words as a result of the nasal mutation, are not included in the alphabet.
• ch represents /x/ (voiceless velar fricative)
• dd represents /g/ (voiced dental fricative), like the English th in then.
• ff represents /f/ (voiceless labiodental fricative), like English f, since Welsh f is pronounced like an English v.
• ll represents /ɬ/ (voiceless alveolar lateral fricative)
• ng represents /ŋ/ (velar nasal), the same sound as in English.
• ph represents /f/ (voiceless labiodental fricative)
• rh represents /r̥/ (voiceless alveolar trill), pronounced roughly like the combination hr.
• th represents /θ/ (voiceless interdental fricative)
• Wymysorys
• has the uncommon digraph ao.

In non-Latin alphabets

Digraphs also exist in languages that are not written with the Latin alphabet. For example, modern Greek has the following:

• αι (ai) represents /e̞/
• ει (ei) represents /i/
• οι (oi) represents /i/
• ου (ou) represents /u/
• υι (yi) represents /i/
• γγ (gg) represents /ɡ/
• γκ (gk) represents /ɡ/
• μπ (mp) represents /b/
• ντ (nt) represents /d/

See also

• Trigraph (orthography)
• Diphthong
• Ligature (typography)
• Diacritic
• Alphabets derived from the Latin
• Orthography
• List of all two-letter combinations
• Bigram