Digraph (orthography)
A digraph (from Ancient Greek δίς (dís) 'double' and γράφω (gráphō) 'to write') or digram is a pair of characters used in the orthography of a language to write either a single phoneme (distinct sound), or a sequence of phonemes that does not correspond to the normal values of the two characters combined.
In Middle English, the sequences ⟨ee⟩ and ⟨oo⟩ were used in a similar way, to represent lengthened "e" and "o" sounds respectively; both spellings have been retained in modern English orthography, but the Great Vowel Shift and other historical sound changes mean that the modern pronunciations are quite different from the original ones.
Some languages have a unified orthography with digraphs that represent distinct pronunciations in different dialects (diaphonemes).
This is the result of three historical sound changes: cake was originally /kakə/, the open syllable /ka/ came to be pronounced with a long vowel, and later the final schwa dropped off, leaving /kaːk/.
The Indic alphabets are distinctive for their discontinuous vowels, such as Thai เ...อ /ɤː/ in เกอ /kɤː/.
Some authors, however, indicate it either by breaking up the digraph with a hyphen, as in hogs-head, co-operate, or with a trema mark, as in coöperate, but the use of the diaeresis has declined in English within the last century.
Positional alternative glyphs may help to disambiguate in certain cases: when round, ⟨s⟩ was used as a final variant of long ⟨ſ⟩, and the English digraph for /ʃ/ would always be ⟨ſh⟩.
The case of ambiguity is the syllabic ん, which is written as n (or sometimes m), except before vowels or y where it is followed by an apostrophe as n’.
In Serbo-Croatian: Note that in the Cyrillic orthography, those sounds are represented by single letters (љ, њ, џ).
Among many young people, especially in the western regions of Norway and in or around the major cities, the difference between /ç/ and /ʃ/ has been completely wiped away and are now pronounced the same.
In Polish: In Portuguese: In Spanish: In Welsh: The digraphs listed above represent distinct phonemes and are treated as separate letters for collation purposes.
On the other hand, the digraphs ⟨mh⟩, ⟨nh⟩, and the trigraph ⟨ngh⟩, which stand for voiceless consonants but occur only at the beginning of words as a result of the nasal mutation, are not treated as separate letters, and thus are not included in the alphabet.
Modern Slavic languages written in the Cyrillic alphabet make little use of digraphs apart from ⟨дж⟩ for /dʐ/, ⟨дз⟩ for /dz/ (in Ukrainian, Belarusian, and Bulgarian), and ⟨жж⟩ and ⟨зж⟩ for the uncommon Russian phoneme /ʑː/.
That can be illustrated with Thai in which the diacritic เ, pronounced alone /eː/, modifies the pronunciation of other vowels: In addition, the combination รร is pronounced /a/ or /an/, there are some words in which the combinations ทร and ศร stand for /s/ and the letter ห, as a prefix to a consonant, changes its tonic class to high, modifying the tone of the syllable.
However, some obsolete sequences no longer retain that reading, as in くゎ kwa, ぐゎ gwa, and むゎ mwa, now pronounced ka, ga, ma.
In addition, non-sequenceable digraphs are used for foreign loans that do not follow normal Japanese assibilation patterns, such as ティ ti, トゥ tu, チェ tye / che, スェ swe, ウィ wi, ツォ tso, ズィ zi.
For dialects that do not distinguish ē and ei, the latter spelling is used for a long e, as in へいせい heisei [heːseː] 'Heisei'.
Those digraphs, ㅐ /ɛ/ and ㅔ /e/ (also ㅒ /jɛ/, ㅖ /je/), and in some dialects ㅚ /ø/ and ㅟ /y/, all end in historical ㅣ /i/.
Hangul was designed with a digraph series to represent the "muddy" consonants: ㅃ *[b], ㄸ *[d], ㅉ *[dz], ㄲ *[ɡ], ㅆ *[z], ㆅ *[ɣ]; also ᅇ, with an uncertain value.
Those values are now obsolete, but most of the doubled letters were resurrected in the 19th century to write consonants that did not exist when hangul was devised: ㅃ /p͈/, ㄸ /t͈/, ㅉ /t͈ɕ/, ㄲ /k͈/, ㅆ /s͈/.
[2] However, for various reasons, Unicode sometimes provides a separate code point for a digraph, encoded as a single character.
