Nice thread. I'll bite.
>A monarchy is…
I'll try to answer the definitional question of monarchy by way of dichotomy.
The only part of the definition that I do not think is by dichotomy is the basic dictum: a monarch is monarch by birth. There is no veil of ignorance. There are no platitudes to equality. Personally, I think there is something very powerful and important just about that idea and about making it front and center in a society, but that's beside the point for this thread.
Next is the difference between a pretender and a monarch. Or more importantly and to make the point, the difference between a pretender and a ceremonial monarch. There are many countries that have pretenders who could fill a 'ceremonial' role in the sense of being a public figure in the way Otto von Hapsburg was later in his life, but they are instead known as pretenders to the crown because they have no role in the government. So, a monarch must additionally have some sort of official role in the government.
Next is the difference between a monarch and a despot. Quoting Montesquieu:
>of a monarchy, that the prince should have this power, but in the execution of it should be directed by established laws; of a despotic government, that a single person should rule according to his own will and caprice
In other words, there is some sort of law above the King. Whether it be from the church, aristocracy, parliament, or independent judiciary is no matter. Even if that law provides the King with extraordinary powers, they would still be a King rather than a despot. Or, to put it differently, just as they are born into their position they are born into their power.
Next is the difference between a monarch and an aristocracy, which is broken the moment one person has some sort of extra legal rights over his peers. Even a council of aristocrats, the moment one has the slightest extra power (a veto, for example), would to me become a monarch.
This is not exhaustive, but I believe provides at last some distinguishing characteristics of a monarchy:
-They are born into their position.
-They are born into their powers.
-They have a function in government.
-They clearly have more functions in government than any others who satisfy the above three.
>The power in a monarchy is excersised by …
I leave out the precise institutional arrangement of a monarchy. There are absolute monarchies, there is the balance of powers of the ancien regime, there are parliamentary monarchies, and there are the culturally important ceremonially monarchies. To me they are all monarchies. We can quibble about which kind of those monarchies is the best one, but they are all monarchies.
>Monarchy is legitimised by…
The same way money comes about, the same way law comes about, and the same way language comes about. I would argue there is a certain property of emergence in their legitimisation, and that they are legitimised culturally through a history of birthright and their connection to their lands and country.