The Celtic languages, once spoken widely, survived to modern times only on the fringes of Europe: Ireland, the Highlands of Scotland, Wales, and Brittany. The mythology of these languages derives first from ancient worship, as observed by classical commentators and as revealed by modern archaeology. Written traditions came with the introduction of Christianity, whose scribes never worshipped the older gods. Irish heroic literature, the most extensive in all Celtic languages, embraced four discrete cycles. Welsh came later with a smaller corpus. Still less was recorded in Scottish Gaelic, and narratives from Cornish, Manx, and Breton survive mostly in oral tradition. The current volume seeks to list, describe, and provide reliable spellings from both ancient and modern traditions. Listed are kings, queens, warriors, hermits, and saints, some of whom are historical but about whom many legends have accrued, and others who certainly never existed. Included also are archaelogical sites and shrines, such living creatures as the eagle and salmon, as well as concepts such as kingship. Cross-references exist from other mythologies, such as Classical and Norse, as well as links to the most Celtic of Arthurian figures, such as Merlin. The dictionary summarizes many lengthy narratives, such as The Mabinogion. Where possible, entries feature reliable etymologies and many entries have extensive bibliographical notes, including adaptations in literature. As it explains concepts and narratives, the Dictionary also becomes a handbook of early Celtic culture.