An armigerous clan is a Scottish clan, family or name which is registered with the Court of the Lord Lyon and once had a chief who bore undifferenced arms, but does not have a chief currently recognized as such by Lyon Court. Before 1745 all chiefs had arms; however, not all of these are recorded in the Public Register of All Arms and Bearings in Scotland, which was only established in 1672.
In Scottish heraldry undifferenced arms are only held by chiefs or heads of clans, families, or names. A clan is considered a "noble incorporation" because a clan chief is a title of honour in Scotland and the chief confers his or her noble status onto the clan. Because armigerous clans do not have such chiefs, they are not recognised as noble communities and have no legal standing under Scots law
According to the Council’s definition of an Armigerous Clan, its entirely acceptable to call your clan armigerous clan. There is no accepted or legal definition and the Lyon court doesnt recognise the term. They do however, recognise Armigerous families. As a Council where you have, for example a group of Couttses, who cant demonstrate genealogical connections, but where they share the same name and bear arms granted by Lyon in the name of Coutts.
We regard this group as an Armigerous Clan. A Clan being a term in Scotland used to describe family groups consisting of different people who often claim descent from a common ancestor but who cannot prove that descent. Usually but not always, an armigerous family consists of those who can prove descent from a common ancestor. In some cases the Clan may consist of people with different surnames (such as the Clan Alpine, which consists of MacGregors, MacQuarrie’s, MacKinnons etc).