There is a massively long thread somewhere on this site re the nomenclature issue, but as Manitas says, in Ireland, the more common name is a button accordion ( or accordeon) for what is known in England as a melodeon. I have a B/C two row button accordion which looks identical to the same manufacturer's G/D melodeon. If asked. I tell folk my instrument is a button accordion, but it doesn't really worry me what people call it unless they call it a concertina!