A Brythonic Goddess, Ratis is known from two inscriptions found in forts sited along Hadrian's wall which ran the east-west length of northern England for the purpose of keeping raiding Scottish warriors on their own side of the border. The first of thse is from the Fort and Settlement of Bridoswald, Cumbria (which may be the site of the fabled fort at Camboglanna) [RIB 1903] and this reads: DEA RATI VOTVM IN PERPETVO (To the Goddess Ratis, a Permanent Offering). The next inscription comes from an altarstone found at CILVRNVM, the Hadrain's Wall Fort at Chesters, Northumberland [RIB 1454] and reads: DEA RAT VSL (To the Goddess Rat[is], a vow freely fulfilled).
The name Ratis has two possible derivatons from the reconstructed proto-Celtic roots *rati- (fern) [which is etymologically linked to *retō- (to run)] or *rƒti- (fort, rampart). However, given the military association the second derivation seems likely, giving us 'Goddess of the Fort' as a meaning for the goddess name. This etymology is supported by the name of the tribal city of the Coritani, Ratae Coritanorum (Fort of the Coritani).
The name component rati/ratis is preserved in several place names: Ratisbon in Southern Germany, Ratiatum (modern Reze in France) and Argantoratum ('Silver Fort', the ancient name of modern Strasbourg). However, it cannot be asserted whether these were places dedicated to the goddess Ratis or simply contained the Celtic noun 'fort'.
