From the Guardian

"Why is Celtic pronounced Seltic rather than Keltic, as it is in every other context?"

A tricky one this. Ed Mortimer started us off. "The answer is simple," he said. "We are wrong to pronounce the word Keltic. It's one of those words where the pronunciation has changed for some reason in one context but not in others. Following the general rule that 'c' followed by 'e' or 'i' is pronounced as an 's', we have Seltik, as in the football club. The same pronunciation used to apply to the adjective describing the ancient inhabitants of the western fringes of Europe, including parts of modern-day Scotland, England, Ireland, Wales, France and Spain. The 's' pronunciation still applies in French, Breton and Galician - but for some reason English has changed to the keltic variant. Put simply, the football club pronunciation is the right one."

Graeme Gardiner offered an alternative view. "Celtic were founded in 1888 to benefit the Irish immigrant population of Glasgow's east end. The name Celtic was chosen to reflect the common roots of the Scots and Irish, who were on the receiving end of considerable sectarian prejudice. Unfortunately the name wasn't used much outside academic circles and was simply mispronounced by the local population. Of course the de facto pronunciation among the faithful is Sellick."


However, the truth, if it is to be had, seemed to be that both pronunciations are ostensibly correct, with Keltic having become the more accepted usage only in the last 30 years. Celtic, having been formed in the last century, naturally retained the Seltic pronunciation. This from the Medieval Scotland website, which a number of readers kindly pointed out:

"The reason the Boston Celtics and Glasgow Celtic and all those other sports teams founded around 1900 (give or take a couple decades) pronounce their names Seltic is not because they were founded by ignorant folk who didn't know any better, but because they spoke English and did know the proper pronunciation of the English word 'Celtic'.

"So what happened? Well, any number of things might explain why the in-crowd pronunciation shifted to Keltic (such as the German influence on Celtic studies, which was strong in the 19th- and early 20th-centuries) but the upshot is that it is now fashionable - almost obligatory - in certain circles to pronounce the word with a K sound rather than the original S sound. In fact, in certain circles (both in and out of academia) it is something of a litmus test - if you don't use the K sound, it will be assumed you are not knowledgeable about things Celtic. But the one and only reason Keltic is now one of the correct pronunciations of the word is because that is how many educated people pronounce it. That is the only logic in the Keltic pronunciation's favour. The standard rules of English, the rules of language, long use and practice, all argue in favour of Seltic, not Keltic. But it still remains that Seltic is a long-established, traditional pronunciation of the word in English. There is absolutely nothing wrong with pronouncing Celtic as Seltic."

KStreet

• How to Pronounce Celtic