Irish orthography has evolved over many centuries, since Old Irish was first written down in the Latin alphabet in about the 8th century AD. Prior to that, Primitive Irish was written in Ogham. Irish orthography is mainly based on etymological considerations, although a spelling reform in the mid-20th century simplified the relationship between spelling and pronunciation somewhat.
There are three main dialect areas of spoken Irish: Ulster (now predominantly in County Donegal), Connacht (Counties Mayo and Galway), and Munster (Counties Kerry, Cork, and Waterford). Some spelling conventions are common to all three dialects, while others vary from dialect to dialect. In addition, individual words may have in a given dialect pronunciations that are not reflected by their spelling (the pronunciation in this article reflects Connacht Irish pronunciation; other accents may differ, but are occasionally included).
The traditional standard Irish alphabet consists of 18 letters: a b c d e f g h i l m n o p r s t u. Thus, it does not contain the following letters used in English: j, k, q, v, w, x, y, z. The vowels may be accented as follows: á é í ó ú.
The acute accent over the vowels, called síneadh fada (meaning "long sign"), is ignored for purposes of alphabetization. Modern loanwords also make use of j k q v w x y z. Of these, v is the most common. It occurs in a small number of words of native origin in the language such as vácarnach, vác and vrác, all of which are onomatopoeic. It also occurs in a number of alternative colloquial forms such as víog instead of bíog and vís instead of bís as cited in Niall Ó Dónaill's Foclóir Gaeilge–Béarla (Irish–English Dictionary). It is also the only non-traditional letter used to write foreign names and words adapted to the Irish language (for example, Switzerland, or Helvetia, is Gaelicised as An Eilvéis; Azerbaijan, in contrast, is written An Asarbaiseáin rather than *An Azarbaijáin). The letters j, q, w, x, y and z are used primarily in scientific terminology or direct, unaltered borrowings from English and other languages, although the phoneme /z/ does exist naturally in at least one dialect, that of West Muskerry, County Cork, as the eclipsis of s. k is the only letter not to be listed by Ó Dónaill. h, when not prefixed to an initial vowel as an aspirate in certain grammatical functions (or when not used as an indicator of lenition when Roman type is used), occurs primarily in loanwords as an initial consonant. The letters' names are spelt out thus:
Tree names were once popularly used to name the letters. Tradition taught that they all derived from the names of Ogham letters, though it is now known that only some of the earliest Ogham letters were named after trees.
Prior to the middle of the 20th century, Irish was usually written using Gaelic script. This typeface, together with Roman type equivalents and letter name pronunciations along with the additional lenited letters, is shown below.
Use of Gaelic type is today almost entirely restricted to decorative and/or self-consciously traditional contexts. The dot above the lenited letter is usually replaced by a following h in the standard Roman alphabet [for example, ċ in Gaelic type becomes ch in Roman type]. The only other use of h in Irish is for vowel-initial words after certain proclitics (e.g. go hÉirinn, "to Ireland") and for words of foreign derivation such as hata "hat".
Although the Gaelic script remained common until the mid-20th century, efforts to introduce Roman characters began much earlier. Theobald Stapleton's 1639 catechism was printed in a Roman type alphabet, and also introduced simplified spellings such as suí for suidhe and uafás for uathbhás, though these did not become standard for another 300 years.
The consonant letters generally correspond to the consonant phonemes as shown in this table. See Irish phonology for an explanation of the symbols used and Irish initial mutations for an explanation of eclipsis. In most cases, consonants are "broad" (velarised) when the nearest vowel letter is one of a, o, u and "slender" (palatalised) when the nearest vowel letter is one of e, i.
Sequences of vowels are common in Irish spelling due to the "caol le caol agus leathan le leathan" ("slender with slender and broad with broad") rule. This rule states that the vowels on either side of any consonant must be both slender (e or i) or both broad (a, o or u), to unambiguously determine the consonant's own broad vs. slender pronunciation. An apparent exception is the combination ae, which is followed by a broad consonant despite the e.
In spite of the complex chart below, pronunciation of vowels in Irish is mostly predictable from a few simple rules:
The following series of charts indicates how written vowels are generally pronounced. Each dialect has certain divergences from this general scheme, and may also pronounce some words in a way that does not agree with standard orthography.
A vowel or digraph followed by i is usually pronounced as that vowel. The i is not pronounced in that case, and just indicates that the following consonants are slender. However, it may be pronounced in the digraphs ei, oi, ui.
When followed by the lenited consonants bh, dh, gh or mh, a stressed vowel usually forms a diphthong.
For aidh, aigh, adh, eadh, idh and igh, see also Special pronunciations in verb forms.
Vowels with a fada are always pronounced long. In digraphs and trigraphs containing a vowel with an acute, only the vowel with the accent mark is usually pronounced, but there are several exceptions, for instance in trigraphs where the two letters without an accent are right next to one another rather than on either side of the accented vowel.
Fada vowels will occasionally also appear in succession, where adjacent vowels are not pronounced: séú /ˈʃeːuː/ "sixth", ríúil /ˈɾˠiːuːlʲ/ "royal, kingly, majestic", báíocht /ˈbˠaːiːxt̪ˠ/ "sympathy", etc.
In the sequence of short vowel + /l, n, r/ + labial, palatal, or velar consonant (except for voiceless stops) within the same morpheme, an unwritten /ə/ gets inserted between the /l, n, r/ and the following consonant:
The rules of epenthesis do not apply across morpheme boundaries (e.g. after prefixes and in compound words):
In verb forms, some letters and letter combinations are pronounced differently from elsewhere.
-(a)idh and -(a)igh are pronounced /ə/ before a pronoun, otherwise /iː/:
In the future and conditional, f (broad or slender) has the following effects:
In the past participle th (also t after d) is silent but makes a voiced obstruent voiceless:
Irish spelling makes use today of only one diacritic, and formerly used a second. The acute accent (Irish: síneadh fada "long sign") is used to indicate a long vowel, as in bád /bˠaːd̪ˠ/ "boat". However, there are some circumstances under which a long vowel is not indicated by an acute, namely:
The overdot (Irish: ponc séimhithe "dot of lenition", buailte "struck", or simply séimhiú, "lenition") was formerly used, especially in Gaelic script, to indicate the lenited version of a consonant; currently a following letter h is used for this purpose. Thus the letters ḃ ċ ḋ ḟ ġ ṁ ṗ ṡ ṫ are equivalent to bh ch dh fh gh mh ph sh th. In Old Irish orthography, the dot was used only for ḟ ẛ (ṡ), while the following h was used for ch ph th; lenition of other letters was not indicated. Later the two systems spread to the entire set of lenitable consonants and competed with each other. Eventually the standard practice was to use the dot when writing in Gaelic script and the following h when writing in Roman letters.
As with most European languages such as Spanish or German, Irish diacritics must be preserved in uppercase forms. If diacritics are unavailable (for example, on a computer using ASCII), there is no generally accepted standard for replacing it (unlike some languages like German, where the umlaut is replaced by a following e and ß is replaced by ss), and so it is generally just omitted entirely or replaced with an apostrophe (especially in names, for example Dara O'Briain rather than Dara Ó Briain).
Lower-case i has no tittle in Gaelic script, and road signs in the Republic of Ireland, which use a typeface based on Transport, also use a dotless lowercase i (as well as a Latin alpha glyph for a). However, as printed and electronic material like books, newspapers and web pages use Roman hand almost invariably, the tittle is generally shown but it is not a diacritic and has no significance. (In Irish, the graphemic distinction between dotted i and dotless ı does not arise, i.e. they are not different letters as they are in, for example, Turkish and Azeri).
According to Alexei Kondratiev, the dotless i was developed by monks in the manuscripts to denote the modification of the letter following it. In the word go deimhin for example, the first i would be dotless, softening the m, and the second dotted i would be a normal vowel. The dotting of every occurrence of i in Irish became a convention, as did the letter h, when the language became more usually typed than handwritten, and the limitations of the machine to accommodate a scribe's flicks and notations imposed standardization. This meant that "letters" that were more intended to modify other letters (h and dotless i) became equal letters.
In general, punctuation marks are used in Irish much as they are in English. One punctuation mark worth noting is the Tironian et ⁊ which is generally used to abbreviate the word agus "and", much as the ampersand is generally used to abbreviate the word and in English.
The hyphen (Irish: fleiscín) is used in Irish after the letters t and n when these are attached to a masculine vowel-initial word through the rules of the initial mutations, as in an t-arán "the bread", a n-iníon "their daughter". However, the hyphen is not used when the vowel is capitalised, as in an tAlbanach "the Scotsman", Ár nAthair "Our Father". No hyphen is used with the h that is attached to a vowel-initial word: a hiníon "her daughter".
The hyphen is also used in compound words under certain circumstances:
Capitalisation rules are similar to English. However, a prefix letter remains in lowercase when the base initial is capitalised (an tSín "China"). For text written in all caps, the prefix letter is often kept in lowercase, or small caps (STAIR NA HÉIREANN "THE HISTORY OF IRELAND"). An initial capital is used for:
Irish has a number of abbreviations, most of which, like lch. for leathanach ("p."/"page") and m.sh. for mar shampla ("e.g."/"for example" "exempli gratia") are straightforward. Two that may require explanation are .i. (which begins and ends with a full stop) for eadhon ("i.e."/"that is") and ⁊rl. or srl. for agus araile ("etc."/"and so forth" "et cetera").
The literary Classical Irish which survived till the 17th century was already archaic and its spelling reflected that; Theobald Stapleton's 1639 catechism was a first attempt at simplification. The classical spelling represented a dialect continuum including distinctions lost in all surviving dialects by the Gaelic revival of the late 19th century. The issue of simplifying spelling, linked to the use of Roman or Gaelic type, was controversial in the early decades of the 20th century. The Irish Texts Society's 1904 Irish–English bilingual dictionary by Patrick S. Dinneen used traditional spellings. After the creation of the Irish Free State in 1922, all Acts of the Oireachtas were translated into Irish, initially using Dinneen's spellings, with a list of simplifications accruing over the years. When Éamon de Valera became President of the Executive Council after the 1932 election, policy reverted to older spellings, which were used in the enrolled text of the 1937 Constitution. In 1941, de Valera decided to publish a "popular edition" of the Constitution with simplified spelling and established a committee of experts, which failed to agree on recommendations. Instead, the Oireachtas' own translation service prepared a booklet, Litriú na Gaeilge: Lámhleabhar an Chaighdeáin Oifigiúil, published in 1945. The following are some old spellings criticised by T. F. O'Rahilly and their simplifications:
The booklet was expanded in 1947, and republished as An Caighdeán Oifigiúil ("the official standard") in 1958, combined with the standard grammar of 1953. It attracted initial criticism as unhistorical and artificial; some spellings fail to represent the pronunciation of some dialects, while others preserve letters not pronounced in any dialect. Its status was reinforced by use in the civil service and as a guide for Tomás de Bhaldraithe's 1959 English–Irish dictionary and Niall Ó Dónaill's 1977 Irish–English dictionary. A review of the written standard, including spelling, was announced in 2010, with a view to improving "simplicity, internal consistency, and logic". The result was the 2017 updated Caighdeán Oifigiúil.