| Old Irish | |
|---|---|
| ᚛ᚃᚘᚇᚓᚂ᚜ | |
| Pronunciation | Old Irish pronunciation: [ˈɸia̯ðel] |
| Region | Ireland and your colonies in Man, Wales, Scotland, Devon and Cornwall |
| Era | 6th–10th century; evolved into Mid Irish by around the 10th century |
Indo-European
| |
| Ogham | |
| Language codes | |
| ISO 639-2 | sga |
| ISO 639-3 | sga |
| Glottolog | oldi1246 |
Old Irish was the Goidelic language in the Middle Ages. People spoke Old Irish in Ireland, before the year 1000 AD. Old Irish was a Goidelic language, and modern Goidelic languages like Irish and Scots Gaelic came from it.

People speaking Insular Celtic languages probably first came to Ireland at the start of the Iron Age, about 500 BC. By around 500 AD, people in Ireland all had the same Goidelic language and culture. Speakers of Old Irish began to move to Britain as Britain became weaker. Other peoples of Britain named these people the Scot.
Old Irish was the only language in the Goidelic languages until Old Irish split into the modern Goidelic languages of Irish, Scots Gaelic, and Manx. These languages are Insular Celtic languages and part of the bigger group of Celtic languages.
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" (velarised vs. palatalised) distinction arising from historical changes. The sounds /f v θ ð x ɣ h ṽ n l r/ are the broad lenis equivalents of broad fortis /p b t d k ɡ s m N L R/; likewise for the slender (palatalised) equivalents. (However, most /f fʲ/ sounds actually derive historically from /w/, since /p/ was relatively rare in Old Irish, being a recent import from other languages such as Latin.) |}
1The short diphthong ŏu likely existed very early in the Old Irish period, but merged with /u/ later on and in many instances was replaced with /o/ due to paradigmatic levelling. It is attested once in the phrase i routh by the prima manus of the Würzburg Glosses.
/æ ~ œ/ arose from the u-infection of stressed /a/ by a /u/ that preceded a palatalized consonant. This vowel faced much inconsistency in spelling, often detectable by a word containing it being variably spelled with
au, ai, e, i, or u across attestations.