English can be confusing — just consider the different sounds of through, though, bough, tough and cough. You might think that names like Sean Bean, Sean Dean, and Sean Lean are more examples of this. However, Sean is an Irish name (or, more broadly, Gaelic: Sean Connery, perhaps the most famous Sean, is Scottish). And, allowing for dialects, the Irish language is relatively consistent in its spelling and pronunciation; you just have to know what the rules are.
Strictly, the name Sean is spelt Seán, that is, with an accent over the letter a:
|Seán||shawn||Irish equivalent of "John"|
From this, you can see that the accent broadens the a from a short ah (as in can) to a long aw (as in paw).
But where does the h sound come from, and how come the e isn't heard? Surprisingly, there's a similarity here between Irish and some languages that are otherwise very different, such as Spanish and Italian. In Italian, a c before a, o, or u (the "broad" vowels) is pronounced like a k. However, before i or e, an Italian c changes to what an English-speaker would write as ch — which is why the last syllable of arrivederci sounds like the start of cheese, for example. Moreover, an extra vowel is sometimes thrown in only to change the sound of a c to ch. This explains the curious spelling of the Italian word that sounds like chow but is written ciao.
A similar game is played in Irish, but with the letter s: An s before a broad vowel (a, o, or u) has the usual sound but before a slender vowel (i or e) it's pronounced sh. For example:
|sos||suss||a break or pause|
And, just like the mysterious i in the Italian word ciao, the letter e in Seán serves only to change the sound of the S to Sh.
Popular Irish names are frequently changed to make them more "phonetic". Caitlín is a notable example: the conventional anglophone spelling is Kathleen. Confusingly, a name's pronunciation may be changed instead of its spelling. Thus, someone living in North America might spell her name Caitlin but expect to hear it pronounced like the name Kate-Lynn.
Even within Ireland, certain Irish names are now often pronounced according to the phonetic conventions of English. Brian, for example, is almost invariably pronounced with a y rather than an ee sound. Similarly, Niall is now usually heard to rhyme with dial — unless the anglicized spelling Neil is used.
Other versions of John include Jean, Jan, Johann, Juan, and Ivan. That the Irish Seán has an initial S instead of a J is explained by the traditional absence of the letter J from the Irish alphabet. Welsh, another Celtic language, also lacks the letter J. Although it is a rather different language, the Welsh for John, Sion, is similar in spelling and pronunciation to the Irish version (the i in Sion serves the same function as the e in Seán).
In Irish, the rule that an s followed by a slender vowel is pronounced sh is strong enough even to penetrate an intervening consonant:
|sleán||shlawn||a kind of spade|
Irish and Italian are not related except in that they are both Indo-European languages: Ireland was not invaded by the Romans and Irish is older than the Romance languages (and English). However, the Roman alphabet was adopted for written Irish. In turn, Irish monks preserved Latin as a written language of learning during the Dark Ages in Europe; they also adopted the convention of using spaces to separate written words (the Romans ran them together).
- Michael Breen
The English-Irish dictionary provides conjugation of Irish verbs as well as word translations.
The Omniglot page on Irish shows the old Irish Uncial version of the Latin alphabet (which is no longer used) and has a useful collection of Irish language links. This website has good general introductions to many other languages too.
Irish influences on orthography: the Wikipedia has an article on interword separation. Orest Ranum has also written a comprehensive review of Paul Saenger's book "Space between Words; the Origins of Silent Reading".