Answer by Bruce Gaston:
First of all, the pseudo-Gaelic spelling "craic" is misleading. The word is actually of English origin, and the usual spelling is therefore "crack". The spelling "craic" is certainly spreading, probably because people think that the word is Irish because it's only used in Ireland, and therefore the Irish-looking spelling is more accurate.
However you spell it, it derives from the Old English cracian meaning "to make an explosive noise, to resound" (rather like the modern onomatopoeic use of "crack", as in "firecracker", "to crack a whip" etc.). In Middle English it developed several closely related meanings: "to make a loud noise", "to brag or boast", "to gossip" or "(to have) a lively conversation". It's used, for example, by the Elizabethan poet Spenser in The Faerie Queene: "vainglorious crakes" i.e. braggarts (Book II, xi, 8). It died out in standard English but persisted in dialect. The sense "lively conversation, gossip, news" (which is the sense closest to Hiberno-English usage) is well attested in northern England and Scotland up to the twentieth century. (Source: OED)
Joseph Wright's English Dialect Dictionary (1933) also gives examples of this use of "crack" in the north of Ireland in the 1880s. It was presumably brought over by English or (more likely) Scottish settlers. In Ireland it then extended its meaning to mean "fun, entertainment" (often with the implication that such fun occurs with friends in a pub), giving phrases like "it was good crack".
Much more recently, Irish media and tourist organisations introduced the spelling "craic", presumably because they were worried foreign tourist might assume expressions such as "that was great crack we had last night" had something to do with a well-known cocaine derivative. (I can't prove that, but I think most Irish people treat this new spelling with a degree of cynicism). Perhaps they just wanted to make it look a bit more Irish for marketing purposes – certainly I find myself not using it any more because it seems to be being degraded into a bit of corny Oirishness.
What do the other Irish English speakers here think about its usage nowadays?
Craic: can someone please explain the origins of this word? by Bruce Gaston