This dictionary of the Breton language was compiled by the French linguist Louis Le Pelletier. Born in Le Mans, Le Pelletier was known for his ability to learn languages and travelled to the abbey of Saint-Mathieu de Fine-Terre in Brittany to become acquainted with Breton.

The dictionary was sponsored by the Estates of Brittany and Le Pelletier spent 25 years preparing the work. It was finished in 1716 but would not be published until 1752. As part of his studies into the language, Le Pelletier compared words found in Breton with those also found in Welsh, noting the close relationship between the two tongues.

Due to its binding, this book was one of those selected by Olwen Hedley in the 1960s as a fine example of bookbinding in the Royal Library at Windsor Castle. Hedley’s ‘Additional Bookbindings’ serve as a supplement to the catalogue of fine bindings compiled in 1893 by the Royal Librarian Richard Rivington Holmes.