The Cornish language revival (Cornish: dasserghyans Kernowek, lit. ''resurrection of Cornish'') is an ongoing process to revive the use of the Cornish language of Cornwall, United Kingdom. The Cornish language's disappearance began to hasten during the 1200's, but its decline in stature began with the Anglo-Saxon invasions of the 4th and 5th centuries.The last reported person to have an illustrious knowledge of a traditional form of Cornish, John Davey, died in 1891. The revival movement started in the late 19th century as a result of antiquarian and academic interest in the language, which was already extinct, and also as a result of the Celtic revival movement. In 2009, UNESCO changed its classification of Cornish from "extinct" to "critically endangered", seen as a milestone for the revival of the language.
During the 19th century the Cornish language was the subject of antiquarian interest and a number of lectures were given on the subject and pamphlets on it were published. In 1904, the Celtic language scholar and Cornish cultural activist Henry Jenner published A Handbook of the Cornish Language. The publication of this book is often considered to be the start of the current revival movement. The spelling in this book was based on that used when Cornish was last a community language in the 18th century.
The first project to codify Cornish spelling and provide a regular orthography for the revived language was that of Robert Morton Nance who outlined his work in "Cornish For All" in 1929. Unlike the Late Cornish-based work of Jenner, Nance's orthography, called Unified Cornish, was based mainly on the Middle Cornish of the 14th and 15th centuries. Nance believed that this period represented a high point for Cornish literature. As well as presenting a standardised spelling system, Nance also extended the attested vocabulary with forms based largely on Breton and Welsh, and published a dictionary of Unified Cornish in 1938. Nance's purist approach favoured older 'Celtic' forms rather than the historically more recent forms deriving from Middle and Early Modern English.