Digraph (orthography)

This article contains phonetic transcriptions in the International Phonetic Alphabet (IPA). For an introductory guide on IPA symbols, see Help:IPA. For the distinction between [ ], / / and ⟨ ⟩, see IPA § Brackets and transcription delimiters.

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 Welsh, the digraph ⟨ll⟩ fused for a time into a ligature.

Some digraphs represent phonemes that cannot be represented with a single character in the writing system of a language, like ⟨ch⟩ in Spanish chico and ocho. Other digraphs represent phonemes that can also be represented by single characters. A digraph that shares its pronunciation with a single character may be a relic from an earlier period of the language when the digraph had a different pronunciation, or may represent a distinction that is made only in certain dialects, like the English ⟨wh⟩. Some such digraphs are used for purely etymological reasons, like ⟨ph⟩ in French.

In some orthographies, digraphs (and occasionally trigraphs) are considered individual letters, which means that they have their own place in the alphabet and cannot be separated into their constituent places graphemes when sorting, abbreviating, or hyphenating words. Digraphs are used in some romanization schemes, e.g. ⟨zh⟩ as a romanisation of Russian ⟨ж⟩.

The capitalisation of digraphs can vary, e.g. ⟨sz⟩ in Polish is capitalized ⟨Sz⟩ and ⟨kj⟩ in Norwegian is capitalized ⟨Kj⟩, while ⟨ĳ⟩ in Dutch is capitalized ⟨Ĳ⟩ and word initial ⟨dt⟩ in Irish is capitalized ⟨dT⟩.

Digraphs may develop into ligatures, but this is a distinct concept: a ligature involves the graphical fusion of two characters into one, e.g. when ⟨o⟩ and ⟨e⟩ become ⟨œ⟩, e.g. as in French cœur "heart".

Double letters

Digraphs may consist of two different characters (heterogeneous digraphs) or two instances of the same character (homogeneous digraphs). In the latter case, they are generally called double (or doubled) letters.

Doubled vowel letters are commonly used to indicate a long vowel sound. This is the case in Finnish and Estonian, for instance, where ⟨uu⟩ represents a longer version of the vowel denoted by ⟨u⟩, ⟨ää⟩ represents a longer version of the vowel denoted by ⟨ä⟩, and so on. 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.

Doubled consonant letters can also be used to indicate a long or geminated consonant sound. In Italian, for example, consonants written double are pronounced longer than single ones. This was the original use of doubled consonant letters in Old English, but during the Middle English and Early Modern English period, phonemic consonant length was lost and a spelling convention developed in which a doubled consonant serves to indicate that a preceding vowel is to be pronounced short. In modern English, for example, the ⟨pp⟩ of tapping differentiates the first vowel sound from that of taping. In rare cases, doubled consonant letters represent a true geminate consonant in modern English; this may occur when two instances of the same consonant come from different morphemes, for example ⟨nn⟩ in unnatural (un+natural) or ⟨tt⟩ in cattail (cat+tail).

In some cases, the sound represented by a doubled consonant letter is distinguished in some other way than length from the sound of the corresponding single consonant letter:

In Welsh and Greenlandic, ⟨ll⟩ stands for a voiceless lateral consonant, while in Spanish and Catalan it stands for a palatal consonant.
In several languages of western Europe, including English, French, Portuguese and Catalan, the digraph ⟨ss⟩ is used between vowels to represent the voiceless sibilant /s/, since an ⟨s⟩ alone between vowels normally represents the voiced sibilant /z/.
In Spanish, Portuguese, Catalan and Basque, ⟨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 those languages).
In Spanish, the digraph ⟨nn⟩ formerly indicated /ɲ/ (a palatal nasal); it developed into the letter ñ.
In Basque, double consonant letters generally mark palatalized versions of the single consonant letter, as in ⟨dd⟩, ⟨ll⟩, ⟨tt⟩. However, ⟨rr⟩ is a trill that contrasts with the single-letter flap, as in Spanish, and the palatal version of ⟨n⟩ is written ⟨ñ⟩.

In several European writing systems, including the English one, the doubling of the letter ⟨c⟩ or ⟨k⟩ is represented as the heterogeneous digraph ⟨ck⟩ instead of ⟨cc⟩ or ⟨kk⟩ respectively. In native German words, the doubling of ⟨z⟩, which corresponds to /ts/, is replaced by the digraph ⟨tz⟩.

Pan-dialectical digraphs

Some languages have a unified orthography with digraphs that represent distinct pronunciations in different dialects (diaphonemes). For example, in Breton there is a digraph ⟨zh⟩ that represents [z] in most dialects, but [h] in Vannetais. Similarly, the Saintongeais dialect of French has a digraph ⟨jh⟩ that represents [h] in words that correspond to [ʒ] in standard French. Similarly, Catalan has a digraph ⟨ix⟩ that represents [ʃ] in Eastern Catalan, but [jʃ] or [js] in Western Catalan–Valencian.

Split digraphs

The pair of letters making up a phoneme are not always adjacent. This is the case with English silent e. For example, the sequence a_e has the sound /eɪ/ in English cake. 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/. Later still, the vowel /aː/ became /eɪ/. There are six such digraphs in English, ⟨a_e, e_e, i_e, o_e, u_e, y_e⟩.^[1]

However, alphabets may also be designed with discontinuous digraphs. In the Tatar Cyrillic alphabet, for example, the letter ю is used to write both /ju/ and /jy/. Usually the difference is evident from the rest of the word, but when it is not, the sequence ю...ь is used for /jy/, as in юнь /jyn/ 'cheap'.

The Indic alphabets are distinctive for their discontinuous vowels, such as Thai เ...อ /ɤː/ in เกอ /kɤː/. Technically, however, they may be considered diacritics, not full letters; whether they are digraphs is thus a matter of definition.

Ambiguous letter sequences

Some letter pairs should not be interpreted as digraphs but appear because of compounding: hogshead and cooperate. They are often not marked in any way and so must be memorized as exceptions. 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. When it occurs in names such as Clapham, Townshend, and Hartshorne, it is never marked in any way. 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⟩.

In romanization of Japanese, the constituent sounds (morae) are usually indicated by digraphs, but some are indicated by a single letter, and some with a trigraph. 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’. For example, the given name じゅんいちろう is romanized as Jun’ichirō, so that it is parsed as "Jun-i-chi-rou", rather than as "Ju-ni-chi-rou". A similar use of the apostrophe is seen in pinyin where 嫦娥 is written Chang'e because the g belongs to the final (-ang) of the first syllable, not to the initial of the second syllable. Without the apostrophe, Change would be understood as the syllable chan (final -an) followed by the syllable ge (initial g-).

In alphabetization

In some languages, certain 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 that composes them, for purposes of orthography and collation:

In the Gaj's Latin alphabet used to write Serbo-Croatian, the digraphs ⟨dž⟩, ⟨lj⟩ and ⟨nj⟩, which correspond to the single Cyrillic letters ⟨џ⟩, ⟨љ⟩, ⟨њ⟩, are treated as distinct letters.
In the Czech and Slovak alphabet, ⟨ch⟩ is treated as a distinct letter, coming after ⟨h⟩ in the alphabet. Also, in the Slovak alphabet the relatively rare digraphs ⟨dz⟩ and ⟨dž⟩ are treated as distinct letters.
In the Danish and Norwegian alphabet, the former digraph ⟨aa⟩, where it appears in older names, is sorted as if it were the letter ⟨å⟩, which replaced it.
In the Norwegian alphabet, there are several digraphs and letter combinations representing an isolated sound.
In the Dutch alphabet, the digraph ⟨ij⟩ is sometimes written as a ligature and may be sorted with ⟨y⟩ (in the Netherlands, though not usually in Belgium); however, regardless of where it is used, when a Dutch word starting with ⟨ij⟩ is capitalized, the entire digraph is capitalized (IJmeer, IJmuiden). Other Dutch digraphs are never treated as single letters.
In Hungarian, the digraphs ⟨cs⟩, ⟨dz⟩, ⟨gy⟩, ⟨ly⟩, ⟨ny⟩, ⟨sz⟩, ⟨ty⟩, ⟨zs⟩, and the trigraph ⟨dzs⟩, have their own places in the alphabet (where e.g. ⟨ny⟩ comes right after ⟨n⟩)
In Spanish, the digraphs ⟨ch⟩ and ⟨ll⟩ were formerly treated as distinct letters, but are now split into their constituent letters.
In Welsh, the alphabet includes the digraphs ⟨ch⟩, ⟨dd⟩, ⟨ff⟩, ⟨ll⟩, ⟨ng⟩, ⟨ph⟩, ⟨rh⟩, ⟨th⟩. However, ⟨mh⟩, ⟨nh⟩ and ⟨ngh⟩, which represent mutated voiceless consonants, are not treated as distinct letters.
In the romanization of several Slavic countries that use the Cyrillic script, letters like ш, ж, and ю might be written as sh, zh and yu, however sometimes the result of the romanization might modify a letter to be a diacritical letter instead of a digraph.
In Maltese, two digraphs are used, ⟨għ⟩ which comes right after ⟨g⟩, and ⟨ie⟩ which comes right after ⟨i⟩.

Most other languages, including most of the Romance languages, treat digraphs as combinations of separate letters for alphabetization purposes.

Examples

Latin script

English

English has both homogeneous digraphs (doubled letters) and heterogeneous digraphs (digraphs consisting of two different letters). Those of the latter type include the following:

⟨sc⟩ normally represents /s/ (voiceless alveolar fricative - scene) or /ʃ/ (voiceless postalveolar fricative - conscious) before ⟨e⟩ or ⟨i⟩.
⟨ng⟩ represents /ŋ/ (velar nasal) as in thing.
⟨ch⟩ usually corresponds to /tʃ/ (voiceless postalveolar affricate - church), to /k/ (voiceless velar plosive) when used as an etymological digraph in words of Greek origin (christ), less commonly to /ʃ/ (voiceless postalveolar fricative) in words of French origin (champagne).
⟨ck⟩ corresponds to /k/ as in check.
⟨gh⟩ represents /ɡ/ (voiced velar plosive) at the beginning of words (ghost), represents /f/ (voiceless labiodental fricative in enough) or is silent at the end of words (sigh).
⟨ph⟩ represents /f/ (voiceless labiodental fricative), as in siphon.
⟨rh⟩ represents English /r/ in words of Greek origin, such as rhythm.
⟨sh⟩ represents /ʃ/ (voiceless postalveolar fricative), as in sheep.
⟨ti⟩ usually represents /ʃ/ word-medially before a vowel, as in education.
⟨th⟩ usually corresponds to /θ/ (voiceless interdental fricative) in thin or /ð/ (voiced interdental fricative) in then. See also Pronunciation of English ⟨th⟩.
⟨wh⟩ represents /hw/ in some conservative dialects; /w/ in other dialects (while); and /h/ in a few words in which it is followed by ⟨o⟩, such as who and whole. See also Phonological history of ⟨wh⟩.
⟨zh⟩ represents /ʒ/ in words transliterated from Slavic languages^[which?], and in American dictionary pronunciation spelling.
⟨ci⟩ usually appears as /ʃ/ before vowels, like in facial and artificial. Otherwise it is /si/ as in fancier and icier or /sɪ/ as in acid and rancid.
⟨wr⟩ represents /r/. Originally, it stood for a labialized sound, while ⟨r⟩ without ⟨w⟩ was non-labialized, but the distinction has been lost in most dialects, the two sounds merging into a single alveolar approximant, allophonically labialized at the start of syllables, as in red [ɹʷɛd]. See also rhotic consonant.
⟨qu⟩ usually represents /kw/; ⟨q⟩ is conventionally followed by ⟨u⟩ and a vowel letter as in quick, with some exceptions.

Digraphs may also be composed of vowels. Some letters ⟨a, e, o⟩ are preferred for the first position, others for the second ⟨i, u⟩. The latter have allographs ⟨y, w⟩ in English orthography.

English vocalic digraphs
second letter → first letter ↓	⟨...e⟩	⟨...i⟩ ¦ ⟨...y⟩	⟨...u⟩ ¦ ⟨...w⟩	⟨...a⟩	⟨...o⟩
⟨o...⟩	⟨oe¦œ⟩ > ⟨e⟩ – /i/	⟨oi¦oy⟩ – /ɔɪ/	⟨ou¦ow⟩ – /aʊ¦uː¦oʊ/	⟨oa⟩ – /oʊ¦ɔː/	⟨oo⟩ – /uː¦ʊ(¦ʌ)/
⟨a...⟩	⟨ae¦æ⟩ > ⟨e⟩ – /i/	⟨ai¦ay⟩ – /eɪ¦ɛ/	⟨au¦aw⟩ – /ɔː/ (in loanwords: /aʊ/ )	(in loanwords and proper nouns: ⟨aa⟩ – /ə¦ɔː¦ɔl/ )	(in loanwords from Chinese: ⟨ao⟩ – /aʊ/ )
⟨e...⟩	⟨ee⟩ – /iː/	⟨ei¦ey⟩ – /aɪ¦eɪ¦(iː)/	⟨eu¦ew⟩ – /juː¦uː/	⟨ea⟩ – /iː¦ɛ¦(eɪ¦ɪə)/
⟨u...⟩	⟨ue⟩ – /uː¦u/	⟨ui⟩ – /ɪ¦uː/
⟨i...⟩	⟨ie⟩ – /iː(¦aɪ)/

Other languages using the Latin alphabet

In Serbo-Croatian:

⟨lj⟩ corresponds to /ʎ/, (palatal lateral approximant)
⟨nj⟩ corresponds to /ɲ/ (palatal nasal)
⟨dž⟩ corresponds to /d͡ʒ/ (voiced postalveolar affricate)

Note that in the Cyrillic orthography, those sounds are represented by single letters (љ, њ, џ).

In Czech and Slovak:

⟨ch⟩ corresponds to /x/ (voiceless velar fricative), counted as a distinct letter
⟨dz⟩ corresponds to /d͡z/ (voiced alveolar affricate), counted as a distinct letter in Slovak, relatively rare digraph
⟨dž⟩ corresponds to /d͡ʒ/ (voiced postalveolar affricate), counted as a distinct letter in Slovak, relatively rare digraph

In Danish and Norwegian:

The digraph ⟨aa⟩ represented /ɔ/ until 1917 in Norway and 1948 in Denmark, but is today spelt ⟨å⟩. The digraph is still used in older names, but sorted as if it were the letter with the diacritic mark.

In Norwegian, several sounds can be represented only by a digraph or a combination of letters. They are the most common combinations, but extreme regional differences exists, especially those of the eastern dialects. A noteworthy difference is the aspiration of ⟨rs⟩ in eastern dialects, where it corresponds to ⟨skj⟩ and ⟨sj⟩. 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.

⟨kj⟩ represents /ç/
⟨tj⟩ represents /ç/.
⟨skj⟩ represents /ʃ/.
⟨sj⟩ represents /ʃ/.
⟨sk⟩ represents /ʃ/ (before i or y).
⟨ng⟩ represents /ŋ/ as in ng in English thing.

In Catalan:

⟨ll⟩ represents /ʎ/ (palatal lateral approximant)
⟨ny⟩ represents /ɲ/ (palatal nasal)
⟨rr⟩ represents /r/ (post-alveolar trill)
⟨ss⟩ represents /s/ (voiceless alveolar retracted sibilant)
⟨qu⟩ represents /k/ (voiceless velar plosive)
⟨gu⟩ represents /g/ (voiced velar plosive)
postvocalic ⟨ix⟩ represents /ʃ/ (voiceless postalveolar fricative) in Eastern dialects, in Western dialects it represents /jʃ/.

In Dutch:

⟨ij⟩ corresponds to /ɛi/ (see above for its possible status as a separate letter).
⟨ng⟩ represents /ŋ/ (velar nasal)
⟨ch⟩ represents /x/ (voiceless velar fricative)
⟨sj⟩ represents /ʃ/ (voiceless postalveolar fricative)
⟨ie⟩ represents /i/ (close front unrounded vowel)
⟨oe⟩ represents /u/ (close back rounded vowel)
⟨eu⟩ represents /ø/ (close-mid front rounded vowel)

In French:

⟨ch⟩ represents /ʃ/ (voiceless postalveolar fricative)
⟨gn⟩ represents /ɲ/ (palatal nasal)
⟨qu⟩ represents /k/ (voiceless velar stop), typically before historic front vowels

French vocalic digraphs
	⟨...i⟩	⟨...u⟩
⟨a...⟩	⟨ai⟩ – /ɛ¦e/	⟨au⟩ – /o/
⟨e...⟩	⟨ei⟩ – /ɛ/	⟨eu⟩ – /œ¦ø/
⟨o...⟩	⟨oi⟩ – /wa/	⟨ou⟩ – /u(¦w)/

Cyrillic

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/. In Russian, the sequences ⟨дж⟩ and ⟨дз⟩ do occur (mainly in loanwords) but are pronounced as combinations of an implosive (sometimes treated as an affricate) and a fricative; implosives are treated as allophones of the plosive /d̪/ and so those sequences are not considered to be digraphs. Cyrillic has few digraphs unless it is used to write non-Slavic languages, especially Caucasian languages.

Arabic script

Because vowels are not generally written, digraphs are rare in abjads like Arabic. For example, if sh were used for š, then the sequence sh could mean either ša or saha. However, digraphs are used for the aspirated and murmured consonants (those spelled with h-digraphs in Latin transcription) in languages of South Asia such as Urdu that are written in the Arabic script by a special form of the letter h, which is used only for aspiration digraphs, as can be seen with the following connecting (kh) and non-connecting (ḍh) consonants:

Urdu	connecting		non-connecting
digraph:	کھا	/kʰɑː/	ڈھا	/ɖʱɑː/
sequence:	کہا	/kəɦɑː/	ڈہا	/ɖəɦɑː/

Armenian

In the Armenian language, the digraph ու ⟨ou⟩ transcribes /u/, a convention that comes from Greek.

Georgian

The Georgian alphabet uses a few digraphs to write other languages. For example, in Svan, /ø/ is written ჳე ⟨we⟩, and /y/ as ჳი ⟨wi⟩.

Greek

Modern Greek has the following digraphs:

αι (ai) represents /e̞/
ει (ei) represents /i/
οι (oi) represents /i/
ου (oy) represents /u/
υι (yi) represents /i/

They are called "diphthongs" in Greek; in classical times, most of them represented diphthongs, and the name has stuck.

γγ (gg) represents /ŋɡ/ or /ɡ/
τσ (ts) represents the affricate /ts/
τζ (tz) represents the affricate /dz/
Initial γκ (gk) represents /ɡ/
Initial μπ (mp) represents /b/
Initial ντ (nt) represents /d/

Ancient Greek also had the "diphthongs" listed above although their pronunciation in ancient times is disputed. In addition, Ancient Greek also used the letter γ combined with a velar stop to produce the following digraphs:

γγ (gg) represents /ŋɡ/
γκ (gk) represents /ŋɡ/
γχ (gkh) represents /ŋkʰ/

Tsakonian has a few additional digraphs:

ρζ (rz) /ʒ/ (historically perhaps a fricative trill)
κχ (kkh) represents /kʰ/
τθ (tth) represents /tʰ/
πφ (pph) represents /pʰ/
σχ (skh) represents /ʃ/

In addition, palatal consonants are indicated with the vowel letter ι, which is, however, largely predictable. When /n/ and /l/ are not palatalized before ι, they are written νν and λλ.

In Bactrian, the digraphs ββ, δδ, and γγ were used for /b/, /d/, and /ŋg/ respectively.

Hebrew

In the Hebrew alphabet, תס‎ and תש‎ may sometimes be found for צ‎ /ts/. Modern Hebrew also uses digraphs made with the ׳‎ symbol for non-native sounds: ג׳‎ /dʒ/, ז׳‎ /ʒ/, צ׳‎ /tʃ/; and other digraphs of letters when it is written without vowels: וו‎ for a consonantal letter ו‎ in the middle of a word, and יי‎ for /aj/ or /aji/, etc., that is, a consonantal letter י‎ in places where it might not have been expected. Yiddish has its own tradition of transcription and so uses different digraphs for some of the same sounds: דז‎ /dz/, זש‎ /ʒ/, טש‎ /tʃ/, and דזש‎ (literally dzš) for /dʒ/, וו‎ /v/, also available as a single Unicode character װ‎, וי‎ or as a single character in Unicode ױ‎ /oj/, יי‎ or ײ‎ /ej/, and ײַ‎ /aj/. The single-character digraphs are called "ligatures" in Unicode. י‎ may also be used following a consonant to indicate palatalization in Slavic loanwords.

Indic

Most Indic scripts have compound vowel diacritics that cannot be predicted from their individual elements. That can be illustrated with Thai in which the diacritic เ, pronounced alone /eː/, modifies the pronunciation of other vowels:

single vowel sign:	กา	/kaː/,	เก	/keː/,	กอ	/kɔː/
vowel sign plus เ:	เกา	/kaw/,	แก	/kɛː/,	เกอ	/kɤː/

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.

Inuit

Inuktitut syllabics adds two digraphs to Cree:

rk for q: ᙯ qai, ᕿ qi, ᖁ qu, ᖃ qa, ᖅ q

and

ng for ŋ: ᖕ ng

The latter forms trigraphs and tetragraphs.

CJK Characters

Chinese

Several combinations of Chinese characters (Hanzi) formed from two or more different characters that known as digraphs.

Japanese

Two kana may be combined into a C V syllable by subscripting the second; the convention cancels the vowel of the first. That is commonly done for CyV syllables called yōon, as in ひょ (ひ_よ) hyo ⟨hi_yo⟩. They are not digraphs since they retain the normal sequential reading of the two glyphs. 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. (See katakana and transcription into Japanese for complete tables.)

Long vowels are written by adding the kana for that vowel, in effect doubling it. However, long ō may be written either oo or ou, as in とうきょう toukyou [toːkʲoː] 'Tōkyō'. 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'. In loanwords, chōonpu, a line following the direction of the text, as in ビール bīru [biːru] bīru 'beer'. With the exception of syllables starting with n, doubled consonant sounds are written by prefixing a smaller version of tsu (written っ and ッ in hiragana and katakana respectively), as in きって kitte 'stamp'. Consonants beginning with n use the kana n character (written ん or ン) as a prefix instead.

There are several conventions of Okinawan kana that involve subscript digraphs or ligatures. For instance, in the University of the Ryukyu's system, ウ is /ʔu/, ヲ is /o/, but ヲゥ (ヲ_ウ) is /u/.

Korean

As was the case in Greek, Korean has vowels descended from diphthongs that are still written with two letters. 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/.

Ligatures and new letters

Digraphs sometimes come to be written as a single ligature. Over time, the ligatures may evolve into new letters or letters with diacritics. For example sz became ß in German, and "nn" became ñ in Spanish.

In Unicode

Generally, a digraph is simply represented using two characters in Unicode.^[2] However, for various reasons, Unicode sometimes provides a separate code point for a digraph, encoded as a single character.

The DZ and IJ digraphs and the Serbian/Croatian digraphs DŽ, LJ, and NJ have separate code points in Unicode.

Two Glyphs	Digraph	Unicode Code Point	HTML
DZ, Dz, dz	Ǳ, ǲ, ǳ	U+01F1 U+01F2 U+01F3	Ǳ ǲ ǳ
DŽ, Dž, dž	Ǆ, ǅ, ǆ	U+01C4 U+01C5 U+01C6	Ǆ ǅ ǆ
IJ, ij	Ĳ, ĳ	U+0132 U+0133	Ĳ ĳ
LJ, Lj, lj	Ǉ, ǈ, ǉ	U+01C7 U+01C8 U+01C9	Ǉ ǈ ǉ
NJ, Nj, nj	Ǌ, ǋ, ǌ	U+01CA U+01CB U+01CC	Ǌ ǋ ǌ
th	ᵺ	U+1D7A^[3]

References

^ Brooks (2015) Dictionary of the British English Spelling System, p. 460 ff
^ "FAQ – Ligatures, Digraphs and Presentation Forms". The Unicode Consortium: Home Page. Unicode Inc. 1991–2009. Retrieved 2009-05-11.
^ "The Unicode Standard, Version 15.1" (PDF). Unicode. Retrieved 2023-12-20.

[1] Brooks (2015) Dictionary of the British English Spelling System, p. 460 ff

[2] "FAQ – Ligatures, Digraphs and Presentation Forms". The Unicode Consortium: Home Page. Unicode Inc. 1991–2009. Retrieved 2009-05-11.

[3] "The Unicode Standard, Version 15.1" (PDF). Unicode. Retrieved 2023-12-20.

[1]

[2]

[3]