What Is Your Town's Name Made Of? A Spelling-Based Atlas of Place-Name Elements in Britain and Ireland

Place names in Britain and Ireland preserve words from Old English, Old Norse, Latin, the Brittonic languages and Gaelic. They have been studied in depth county by county, but rarely mapped together from open data across both islands. I tag 105,532 names with 67 spelling rules for common elements: 45,632 settlements (OS Open Names for Great Britain; the OSNI and Tailte Éireann gazetteers for Ireland) and 59,900 Irish townlands. 43% of settlements and 44% of townlands carry at least one element. The commonest is the English -ton (5,949 settlements, 16% of England's); Bally- leads among townlands (6,282). Simple profiles show sharp linguistic edges: within 20 to 40 km of the England and Wales border, 31% of settlements on the Welsh side have a Welsh element against 0.5% on the English side, and Cornish elements fall from 27% of settlements in Cornwall to 1.4% in Devon. Settlements with the Latin-derived -chester are towns or cities ten times as often as settlements in general (33% against 3.3%). Official Irish forms for 37,175 names in the Republic allow a test of what anglicised spellings stand for. Most are reliable (Knock- is cnoc, a hill, in 99% of cases), but Kil- is cill, a church, in only 68%, and coill, a wood, in 30%, rising to 95 of 105 Kil- townlands in Monaghan. Spelling rules are a first guess, not an etymology, and the datasets differ in detail; the interactive map lets readers look up any name. Interactive version: https://maps.tristanhotham.com/place-name-endings/. Data and code: https://github.com/Tristan-Hotham/place-name-endings. Blog post: https://blog.tristanhotham.com/2026/10/29/place-name-endings/.