Rhyfel Byd Cyntaf

== Welsh == === Proper noun === y Rhyfel Byd Cyntaf m the First World War, World War III Synonym: y Rhyfel Mawr ==== Coordinate terms ==== yr Ail Ryfel Byd (“the Second World War”) === Mutation === === Further reading === R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke, et al., editors (1950–present), “Rhyfel Byd Cyntaf”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies