The first comprehensive treatment of grammatical number in Welsh - an intriguing, yet relatively neglected area in the study of number phenomena. 

• Comprises major contributions to the study of grammatical number based on a new corpus collected from Middle Welsh texts and a reassessment of data from Old and Modern Welsh
• Approaches number in Welsh from a cross-linguistic perspective, providing data that can be used by Welsh linguists, Celticists, and non-specialized linguists with no previous knowledge of the language
• Offers new answers to whether certain noun types are number categories and explores the significance of literary genre to the study of older language stages
• Integrates both diachronic and typological perspectives, and is based on the full corpus available here: https://zenodo.org/record/3632585#.XjgzwHtS8uU
• Includes new findings on minor numbers, mass nouns and their agreement and the loss of dual number which will prove to be of interest to all linguists