dumnonian/dʌmˈnəʊ.ni.ən/EtymologyFrom Dumnonia + -an. Doublet of Devonian.dumnonian means of or relating to Dumnonia. Lexicurio rates it Sui generis — a strength score of 87 out of 100.dumnonian is pronounced /dʌmˈnəʊ.ni.ən/.adjOf or relating to Dumnonia.nounA native or inhabitant of Dumnonia.