Riverside County and San Bernardino County to the north form this metro area. Like many such metro areas in the Southwest, it extends far into uninhabited desert areas, in this case east through the Mojave Desert to the Nevada/Arizona border. Larger than nine U.S. states, it is often referred to as the Inland Empire.
I agree with tchrist that the word doctor in doctor appointment is a noun (attributive noun I believe), although the definition of an attributive noun is a noun used as an adjective, so maybe it's just semantics at some point.
It is common name , that can be applied to any one of a class just mentioned. Hence it is a Common Noun. A Proper Noun is name of a particular person , Place and or thing.âHolidayâ does not come under the purview of this definition. Hence it is not a Proper Noun. There are examples where a Proper Noun can be used as a Common Noun. Ex: He is a Hercules.