Ah, what a lovely question. The proper noun "Panama" becomes a common noun when we refer to it as a type of geographical feature called an isthmus. Just like how we can call a specific painting "art," we can refer to Panama as an isthmus. Keep exploring the beauty of language, my friend.
The compound noun 'Suez Canal' is a proper noun, the name of a specific place.
As a name of a road , Park Avenue', it is a proper noun, and both words star with a capital letter. However, when used separately, as 'the park, or 'the avenue', they are common nouns and so not need a capital letter.
A proper noun is the name of a specific person, place, or thing. A proper noun for the common noun 'canal' is the name of a canal, such as the Panama Canal, The Suez Canal, or the well known street in New York City, Canal Street.
It is a proper noun, because it is the name of a specific thing.
proper
Proper noun
it's a common noun. a proper noun would be Spider-Man.
Pencil proper or common noun
As given, it is a proper noun, as it is the name of a person. Both words begin with a Capital Letter ; 'Charley Reynolds'. Similarly, The President of the United States of America is 'Mr. Donald Trump'. Note the use of capital letters.
The noun cassette is a common noun.
a common noun?
Camel is a common noun.