… is Regency.
It’s used loosely to designate just about anything in English history/literature/commercial fiction/furniture, circa 1788-1830, which has women simpering and wafting through rooms in muslin gowns with their bosoms hoicked up to their armpits, while the men wear starched cravats and collarpoints up over their ears like earmuffs. As well as anything vaguely to do with Jane Austen or any of her modern imitators, and it’s often synonymous with a period of extravant living, folly, excessive gambling, sexual immorality and fatuity.
But it’s in fact, a specific term for a period of time when George III (1738-1820), because of the effects of the porphyria from which he suffered–the bouts of madness; he was also deaf and blind during the latter stages–was deemed incapable of ruling, and his son, George, was made Regent by an Act of Parliament. And that period is from 28 February 1812 until George III’s death in 1820.
The Prince was also acting Regent during a brief spell between 1788-89 (as dramatised in the film, The Madness of King George).
So, curiously, it has very little to do with fashion and really to do with the legal status of the ruling monarch–who in those days still had quite a bit of power. For example, the ability to appoint a Prime Minister of his liking or to dismiss according to his dislike. And, more importantly, the right to sign or refuse to sign anything. And regardless of Parliament’s wishes or vote on the matter, his word was still law.