We often squabble about things that concern identity: politics, religion, sexuality, race. Add language use to the mix and you get a double helping of discord and pedantry—found, for example, in disputes over both Celtic identity and the pronunciation of the word Celtic. To see what I mean, Google celtic keltic pronunciation forums. And get comfortable.

Growing up in the west of Ireland, I encountered the word Celtic at an early age. I should say words, because I spoke it differently depending on the context. Celtic had a soft c, like “Seltic,” in Celtic Football Club, and a hard c, like “Keltic,” elsewhere—Celtic mythology, Celtic music, The Celts. I wondered about the discrepancy but didn’t figure it out until later.

Celtic pronounced “Keltic” is an outlier in English phonology. Nearly every other English word beginning ce- has a soft-c sound: cedar, ceiling, cell, cement, cent, cereal, certain, cesspit, and so on (cello, with its “ch-” onset, is another anomaly). So it shouldn’t surprise us that “Seltic” was once overwhelmingly the norm. The now-dominant pronunciation “Keltic” is a modern innovation.

We can see the shift by comparing Fowler’s original Dictionary of Modern English Usage with Robert Burchfield’s revised third edition. Here’s Fowler, 1926: “The spelling C-, & the pronunciation s-, are the established ones, & no useful purpose seems to be served by the substitution of k-.” Burchfield, 1996: “Except for the football club Celtic (in Glasgow), which is pronounced /’seltɪk/, both Celt and Celtic are pronounced with initial /k/ in standard English.”

Burchfield doesn’t mention the Boston Celtics, and that’s not his only oversimplification. Celtic may be pronounced either way in standard English—even if this bothers some people. A lot of antagonism over language use stems from misconceptions about correctness, such as the common belief that there can be only one correct form of a word (one meaning, spelling, pronunciation, etc.), and that variants are therefore wrong.

English is more accommodating than this. Variants are often fine and even standard. You can identify legitimate variants with a good modern dictionary. For Celtic, Merriam-Webster, American Heritage, Oxford, Random House, Collins, and Dictionary.com all give both pronunciations, /k/ first. Macmillan, Cambridge, and the OED do likewise for both UK and U.S. English. It’s as strong a consensus as you’ll find. 

People speak like the people around them. They develop accents like those of their families and peers and pick up usages from friends and colleagues. This is one reason the pronunciation of Celtic varies between groups but tends to be consistent within a group. Garner’s Dictionary of Modern American Usage notes that historians “generally prefer the /k/ sound,” while the Columbia Guide to Standard American English reports the same preference among “scholars of Celtic language and literature.”

According to the Merriam-Webster Dictionary of English Usage, “the closer you get to circles substantively concerned with Celtic lore and languages, the more likely you are to hear \'kel-tik\”—though “Seltic” may be heard “at times from very well-educated speakers.” The American Heritage Dictionary elaborates:

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.

English borrowed Celtic in the 17th century from French celtique, soft-c, and from Latin Celtae, also soft-c in Britain at the time (unlike Classical Latin, which used a hard c). Centuries later the pronunciation changed, because language, but it didn’t switch from “Seltic” to “Keltic”—it just added the variant, which then spread. So now we have two acceptable forms. (And two spellings: Keltic, though unusual, is a variant that recalls Greek Keltoi, “the Gauls.”)

English is a hotchpotch of languages and lexicons, originally Germanic but with strong Scandinavian, French, and Latin influences. This can lead to specious arguments based on supposedly self-evident logic: It must be “Seltic” because phonology; It must be “Keltic” because etymology. But neither phonology nor etymology dictates usage—that’s down to us, and we’re a contrary bunch.

Claims about correctness in language can’t override the facts of usage, and the important fact here is that both pronunciations are standard and correct. Don’t believe me? Scroll up and consult the dictionaries. Critics are entitled to dislike “Seltic” or “Keltic,” but they have no business saying either pronunciation is wrong. Because they’re both right.