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

A digraph or digram (from the Ancient Greek: δίς dís, "double" and γράφω gráphō, "to write") 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.

Some digraphs represent phonemes that cannot be represented with a single character in the writing system of a language, like ⟨sh⟩ in English ship and fish. 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 ⟨rh⟩ in English.

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. ⟨ch⟩ in English is capitalized ⟨Ch⟩, 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).

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, 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

Look up Category:English terms with pseudo-digraphs in Wiktionary, the free dictionary.

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 resembling /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 several Slavic languages, e.g. Czech, double letters may appear in compound words, but they are not considered digraphs. Examples: bezzubý 'toothless', cenný 'valuable', černooký 'black-eyed'.

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. For example:

• 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 ⟨cs⟩ follows ⟨c⟩, ⟨dz⟩ and ⟨dzs⟩ follow ⟨d⟩, etc.)
• 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 ч might be written as sh, zh and ch, 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 English, French, German, Polish, etc., treat digraphs as combinations of separate letters for alphabetization purposes.

Examples

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]

See also Ligatures in Unicode.

See also

• Multigraph (orthography)
• Trigraph
• Tetragraph
• Pentagraph
• Hexagraph
• Bigram
• Diphthong
• List of Latin letters
• Digraph (programming)

References