Isatis tinctoria
Greek and Roman writers, in the 1st century BC and the 1st century AD, name the inhabitants of Great Britain and Ireland as the "Priteni", the origin of the Latin word "Britanni". It has been suggested that this name derives from a Gaulish description translated as "people of the forms", referring to the custom of tattooing or painting their bodies with blue woad made from "Isatis tinctoria". Parthenius, a 1st-century Ancient Greek grammarian, and the "Etymologicum Genuinum", a 9th-century lexical encyclopaedia, mention a mythical character Bretannus (the Latinised form of the , "Brettanós") as the father of Celtine, mother of Celtus, the eponymous ancestor of the Celts.