Ah, I can see the cause of the confusion now. Breezy uses the term "a capella" for singing without any instrument, and "unaccompanied" for performing alone with an instrument (e.g. guitar).

I think I'm right in saying that most people (including me) would use "unaccompanied" to mean the same as "a capella", which is why some of you were confused by Breezy's use of "unaccompanied".

I tend to use "solo" to refer to performing by myself, as opposed to in the band or duo (etc.) - I think that's less confusing, and you can use it in conjunction with "unaccompanied" or "a capella" if you like, to indicate performing unaccompanied on your own.

That means you can sing unaccompanied with other people, using the definition above. Which sounds a bit strange, I admit...

Blimey, I think I've confused myself now.