Doh! I didn't know there was confusion about a capella (or other various spellings). When I use it I mean voice only. I'll make a mental note to stop using the term but at my age the mental note may have vanished before I finish this sentence.

Thanks for the correction folks.

McGrath, I'm not sure unaccompanied is a great term either. I wouldn't consider two voices together as unaccompanied let alone a whole song circle. Voice only may be the best term.