The plural of the noun principal is principals (loan values, school heads, or those with a proprietary interest).
The plural of the homophone principle is principles.
In the Bible 'principality' means a kingdom or empire with a ruler. It covers all sizes from a large country to a small city state. In the plural it means the rulers of the world.
I'm looking for the main library in this principality.
Principality of Andorra
Principality of Bitlis ended in 1847.
Principality of Trubetsk ended in 1566.
Principality of Halberstadt was created in 1648.
Principality of Halberstadt ended in 1807.
Principality of Beloozero was created in 1238.
Principality of Abkhazia ended in 1864.
Principality of Mindelheim was created in 1467.
Principality of Wales ended in 1282.
Principality of Wales was created in 1216.