Craic is an English Irish term pronounced "crack" that has many definitions. Many people think of craic as the warm feeling and inviting sound of a busy English or Irish pub---cheerful voices all blending together with the right music played at the right volume.
Other definitions follow:
1. The particular sense of esprit produced by the confluence of drink, romance and music. "we went out to the Lion and Rose last night - a great band was playing. It was great craic!" It can also mean whatever is happening at any particular time and place. He walked into the bar and asked, "What's the craic, lads?"
2. "The craic" is:
A neighborly thing Good music A good drink Excellent company Going with the flow Gift of gab Story telling A good English/Irish welcome
3. Craic Irish word for fun or enjoyment that has been brought into the English language, usually when mixed with alcohol and/or music. "Bhi craic agus ceol againn" : "we had fun and music". Fun doesn't really cut it though. General banter, good times had by all, is more like it. Also a person who is good company.
Craic can be used in a variety of sentences, but in the US one should be careful about how you might sound to the uninitiated! Some examples:
It was great craic! She's great craic when she gets going! He's great craic when he has a few pints of Guinness in him. What's the craic? How's the craic?