Celt·ic (kĕltĭk, sĕl-) also Kelt·ic (kĕl-)
A subfamily of the Indo-European language family comprising the Insular and the Continental branches.
Of or relating to the Celts or their languages.
Usage Note: Although many people pronounce this word with an initial (s) sound, an initial (k) sound is standard in historical, linguistic, and sociological contexts. Interestingly, the introduction of the (k) sound is a linguistic change started by scholars, contravening the historical development of the word. The c was probably pronounced (s), as is usual before e, when the word entered English from French and Latin in the 1600s. The later pronunciation with (k) imitates that of the original Latin word Celtae, a name for the Gauls, the ancient Celtic tribes of France. The (s) pronunciation has no doubt been reinforced by the success and popularity of Boston's professional basketball team, the Celtics, a name that is sometimes shortened to the Celts. Both are always pronounced with the (s) sound.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.