Middle Irish is the Goidelic language spoken in Ireland, Scotland and the Isle of Man from the 10th to the 16th centuries. It is a member of the Insular Celtic branch of the Celtic languages. The modern Goidelic languages—Irish, Scottish Gaelic and Manx—are all descended from Middle Irish.
Middle Irish is attested in a large body of manuscripts, most of them dating from the 12th to the 14th centuries. These manuscripts are mostly in the Latin script, although a few are in the ogham script, and a few are in the Cyrillic script. The majority of the manuscripts are legal texts, although there are also a number of literary texts.
The Irish text known as Lebor na hUidre (The Book of the Dun Cow) is the oldest surviving manuscript in any Goidelic language. It dates from the early 12th century and is written in the ogham script.
Middle Irish was the first Celtic language to be written in the Latin script. This was probably because the majority of the population was literate in Latin, and also because most of the manuscripts that have survived are legal texts.
The earliest surviving examples of Middle Irish literature are the poems known as the Ulster Cycle. These were probably written in the late 12th or early 13th century.
Middle Irish continued to be spoken until the 16th century, when it was gradually replaced by Modern Irish.