a branch of the Indo-European family of languages, divided into Goidelic (Irish, Scottish Gaelic, Manx) and Brythonic (Welsh, Breton, and the extinct Cornish) branches
See Celtic in American Heritage Dictionary 4
(kĕlˈtĭk, sĕlˈ-) also Kelt·ic(kĕlˈ-)
noun
A subfamily of the Indo-European language family comprising the Insular and the Continental branches.
adjective
Of or relating to the Celtic people and languages.