The Welsh Government's tourism minister has declared he will promote Wales as "a principality within the United Kingdom".
Lord Elis-Thomas said the Prince of Wales was as enthusiastic as he was about the idea.
The recently-appointed culture, tourism and sport minister was speaking at a Wales Office reception in London.
Plaid Cymru leader Leanne Wood denounced the idea as an "out-dated gimmick".
The Oxford English Dictionary describes a principality as "the territory held or governed by a prince".
Wales has not been a principality since the 16th century and the Welsh Government itself has denied that Wales is one.
Lord Elis-Thomas told guests at the event: "We are going to promote the principality of Wales as a wonderful principality."
He said "the Prince of Wales is as enthusiastic as I am" about marketing Wales "as a principality within the United Kingdom".
Lord Elis-Thomas joked: "Anybody who doesn't like this word, I will see you at the end."
The Welsh Government said in a statement in 2008: "Wales is not a principality. Although we are joined with England by land, and we are part of Great Britain, Wales is a country in its own right."
On Tuesday, a Welsh Government spokesman told BBC Wales: "This is not Welsh Government policy and we cannot comment further on personal remarks made at an event attended by the minister in a personal capacity."
Lord Elis-Thomas is a former leader of Plaid Cymru who quit the party in 2016 to sit as an independent member of the Welsh Assembly, pledging to support the Labour-led Welsh Government.
First Minister Carwyn Jones appointed him to a junior ministerial post in November, although he has not joined the Labour party.
The Dwyfor Meirionnydd AM's comments prompted an outcry on social media from people who said referring to Wales as a principality diminished its status.
Plaid Cymru leader Leanne Wood said on Twitter: "Wales has so much to offer. Our literature, history, cultures, music, art, language, landscape, waterways, mountains, amazing food, drink & more.
"Ministers should focus on these wonderful strengths to promote our country & forget the out-dated gimmicks."
Jonathan Edwards, Plaid Cymru MP for Carmarthen East and Dinefwr tweeted: "Labour Government Ministers once again rejoicing in Wales' vassal status. What hope for Wales with such inherent subservience guiding the governance of our country".