Y Geiriadur

Geiriadur Prifysgol Cymru is the premier historical dictionary of the Welsh language, comparable in approach and scope to the Oxford English Dictionary. It offers a comprehensive lexicon that documents the evolution of Welsh vocabulary from its earliest texts through the rich literature of the Middle and Modern periods, up to the recent linguistic developments influenced by extensive usage across various life aspects over the past fifty years. The dictionary not only provides definitions in Welsh but also includes English equivalents, with meticulous attention to word forms, combinations, and etymology.

Comprised of over two million entries, the dictionary draws from a continuously growing collection of quotations from various texts. In 2014, a free online version called GPC Ar Lein was launched, featuring all material from the first and second editions along with thousands of new and updated words. Additionally, mobile apps for Apple and Android devices, supported by the Welsh Government, provide easy access to the dictionary’s resources, aiding learners and educators alike. Geiriadur Prifysgol Cymru is a research project based at the National Library of Wales and is backed by the Welsh Government and the University of Wales Trinity Saint David.