- a branch of the Indo-European family of languages, including especially Irish, Scottish Gaelic, Welsh, and Breton, which survive now in Ireland, the Scottish Highlands, Wales, and Brittany.
- of the Celts or their languages.
- a branch of the Indo-European family of languages that includes Gaelic, Welsh, and Breton, still spoken in parts of Scotland, Ireland, Wales, and Brittany. Modern Celtic is divided into the Brythonic (southern) and Goidelic (northern) groups
- of, relating to, or characteristic of the Celts or the Celtic languages
also Keltic, 1650s, of archaeology or history, from French Celtique or Latin Celticus “pertaining to the Celts” (see Celt). In reference to languages, from 1707; of other qualities, 19c. The Boston basketball team was founded 1946. Celtic twilight is from Yeats’s name for his collection of adapted Irish folk tales (1893).