Old Irish

Old Irish, also called Old Gaelic, is the oldest form of the Goidelic/Gaelic language for which there are extensive written texts. It was used from 600 to 900. The main contemporary texts are dated 700–850; by 900 the language had already transitioned into early Middle Irish. Some Old Irish texts date from the 10th century, although these are presumably copies of texts written at an earlier time. Old Irish is forebear to Modern Irish, Manx and Scottish Gaelic.
Old Irish is known for having a particularly complex system of morphology and especially of allomorphy, as well as a complex sound system involving grammatically significant consonant mutations to the initial consonant of a word. Apparently, neither characteristic was present in the preceding Primitive Irish period, though initial mutations likely existed in a non-grammaticalised form in the prehistoric era.
Contemporary Old Irish scholarship is still greatly influenced by the works of a small number of scholars active in the late 19th and early 20th centuries, such as Rudolf Thurneysen and Osborn Bergin.

Notable characteristics

Notable characteristics of Old Irish compared with other old Indo-European languages, are:

Initial mutations, including lenition, nasalisation and aspiration/gemination.
A complex system of verbal allomorphy.
A system of conjugated prepositions that is unusual in Indo-European languages but common to Celtic languages. There is a great deal of allomorphy here, as well.
Infixed or prefixed object prepositions, which are inserted between the verb stem and its initial prefix. If a verb lacks any such prefixes, a dummy prefix is normally added.
Special verbal conjugations are used to signal the beginning of a relative clause.

Old Irish also preserves most aspects of the complicated Proto-Indo-European system of morphology. Nouns and adjectives are declined in three genders ; three numbers ; and five cases. Most PIE noun stem classes are maintained. Most of the complexities of PIE verbal conjugation are also maintained, and there are new complexities introduced by various sound changes.

Classification

Old Irish was the only known member of the Goidelic branch of the Celtic languages, which is, in turn, a subfamily of the wider Indo-European language family that also includes the Slavonic, Italic/Romance, Indo-Aryan and Germanic subfamilies, along with several others. Old Irish is the ancestor of all modern Goidelic languages: Modern Irish, Scottish Gaelic and Manx.
A still older form of Irish is known as Primitive Irish. Fragments of Primitive Irish, mainly personal names, are known from inscriptions on stone written in the Ogham alphabet. The inscriptions date from about the 4th to the 6th centuries. Primitive Irish appears to have been very close to Common Celtic, the ancestor of all Celtic languages, and it had a lot of the characteristics of other archaic Indo-European languages.

Phonology

Consonants

The consonant inventory of Old Irish is shown in the chart [|below]. The complexity of Old Irish phonology is from a four-way split of phonemes inherited from Primitive Irish, with both a fortis–lenis and a "broad–slender" distinction arising from historical changes. The sounds are the broad lenis equivalents of broad fortis ; likewise for the slender equivalents.
Some details of Old Irish phonetics are not known. may have been pronounced or, as in Modern Irish. may have been the same sound as or. The precise articulation of the fortis sonorants is unknown, but they were probably longer, tenser and generally more strongly articulated than their lenis counterparts, as in the Modern Irish and Scottish dialects that still possess a four-way distinction in the coronal nasals and laterals. and may have been pronounced and respectively. The difference between and may have been that the former were trills while the latter were flaps. and were derived from an original fortis–lenis pair.

Vowels

Old Irish had distinctive vowel length in both monophthongs and diphthongs. Short diphthongs were monomoraic, taking up the same amount of time as short vowels, while long diphthongs were bimoraic, the same as long vowels. The inventory of Old Irish long vowels changed significantly over the Old Irish period, but the short vowels changed much less.
The following short vowels existed:
¹The short diphthong likely existed very early in the Old Irish period, but merged with later on and in many instances was replaced with due to paradigmatic levelling. It is attested once in the phrase i routh by the prima manus of the Würzburg Glosses.
arose from the u-infection of stressed by a that preceded a palatalized consonant. This vowel faced much inconsistency in spelling, often detectable by a word containing it being variably spelled with across attestations. Tulach "hill, mound" is the most commonly cited example of this vowel, with the spelling of its inflections including tulach itself, telaig, telocho, tilchaib, taulich and tailaig. This special vowel also ran rampant in many words starting with the stressed prefix air-.
Archaic Old Irish had the following inventory of long vowels:
¹Both and were normally written but must have been pronounced differently because they have different origins and distinct outcomes in later Old Irish. stems from Proto-Celtic *ē, or from ē in words borrowed from Latin. generally stems from compensatory lengthening of short *e because of loss of the following consonant or a directly following vowel in hiatus. It is generally thought that was higher than. Perhaps was while was. They are clearly distinguished in later Old Irish, in which becomes . becomes in all circumstances. Furthermore, is subject to u-affection, becoming or, while is not.
²A similar distinction may have existed between and, both written, and stemming respectively from former diphthongs and from compensatory lengthening. However, in later Old Irish both sounds appear usually as, sometimes as, and it is unclear whether existed as a separate sound any time in the Old Irish period.
³ existed only in early archaic Old Irish ; afterwards it merged into. Neither sound occurred before another consonant, and both sounds became in later Old Irish. The late does not develop into, suggesting that > postdated >.
Later Old Irish had the following inventory of long vowels:
¹Early Old Irish and merged in later Old Irish. It is unclear what the resulting sound was, as scribes continued to use both and to indicate the merged sound. The choice of in the table above is somewhat arbitrary.
The distribution of short vowels in unstressed syllables is a little complicated. All short vowels may appear in absolutely final position after both broad and slender consonants. The front vowels and are often spelled and after broad consonants, which might indicate a retracted pronunciation here, perhaps something like and. All ten possibilities are shown in the following examples:
The distribution of short vowels in unstressed syllables, other than when absolutely final, was quite restricted. It is usually thought that there were only two allowed phonemes: and . The phoneme tended to occur when the following syllable contained an *ū in Proto-Celtic, or after a broad labial. The phoneme occurred in other circumstances. The occurrence of the two phonemes was generally unrelated to the nature of the corresponding Proto-Celtic vowel, which could be any monophthong: long or short.
Long vowels also occur in unstressed syllables. However, they rarely reflect Proto-Celtic long vowels, which were shortened prior to the deletion of inner syllables. Rather, they originate in one of the following ways:

from the late resolution of a hiatus of two adjacent vowels ;
from compensatory lengthening in response to loss of a consonant ;
from assimilation of an unstressed vowel to a corresponding long stressed vowel;
from late compounding;
from lengthening of short vowels before unlenited, still in progress in Old Irish.
Stress

Stress is generally on the first syllable of a word. However, in verbs it occurs on the second syllable when the first syllable is a clitic. In such cases, the unstressed prefix is indicated in grammatical works with a following centre dot.

Orthography

As with most medieval languages, the orthography of Old Irish is not fixed, so the following statements are to be taken as generalisations only. Individual manuscripts may vary greatly from these guidelines.
The Old Irish alphabet consists of the following eighteen letters of the Latin alphabet:
in addition to the five long vowels, shown by an acute accent :
the lenited consonants denoted with a superdot :
and the eclipsis consonants also denoted with a superdot:
Old Irish digraphs include the lenition consonants:
the eclipsis consonants:
the geminatives:
and the diphthongs:
The following table indicates the broad pronunciation of various consonant letters in various environments:
When the consonants b, d, g are eclipsed by the preceding word, their spelling and pronunciation change to: , ,
Generally, geminating a consonant ensures its unmutated sound. While the letter may be voiced at the end of some words, but when it is written double it is always voiceless in regularised texts; however, even final was often written "cc", as in bec / becc "small, little".
In later Irish manuscripts, lenited f and s are denoted with the letter h,, instead of using a superdot,.
When initial s stemmed from Primitive Irish *sw-, its lenited version is .
The slender variants of the 13 consonants, transcribed in IPA with a following, occur in the following environments:

Before a written e, é, i, í
After a written i, when not followed by a vowel letter

Although Old Irish has both a sound and a letter h, there is no consistent relationship between the two. Vowel-initial words are sometimes written with an unpronounced h, especially if they are very short or if they need to be emphasised. On the other hand, words that begin with the sound are usually written without it: a ór "her gold". If the sound and the spelling co-occur, it is by coincidence, as ní hed "it is not".