MikeD, you have stepped into an on-going and sometimes nasty "discussion" here. The general (but not universal) opinion is that "trad", by definition, means that a piece of music is in the public domain, that it has been around for a long time (otherwise not denominated) and that the author is unknown. Of course, that eliminates anything written by O'Carolan, but that's apparently all right. "Acoustic instruments" goes without saying. You might be able to get away with calling it "traditional style" if you stay away from non-acoustic, but I'm sure that there are those who will argue that point.

The whole discussion of trad meaning that no royalties need be paid if somebody else records it is a different, if related, issue.