Early Welsh board-game, often compared to the Irish fidchell and búanfach. While the word is commonly translated as ‘chess’, we lack sufficient information about how it was played to know how it might compare with that game, even though narrative descriptions tell us Peredur and Macsen play it; in Breuddwyd Rhonabwy [The Dream of Rhonabwy], Arthur or Owain play gwyddbwyll on a silver board. Rachel Bromwich discusses the game in Trioedd Ynys Prydain, rev. edn. (Cardiff, 1978), 246.