There is no word 'snoppy' in English. Perhaps you made a typo, or perhaps you need the urban dictionary category.
The word 'Snoopy' (capital S) is a proper nounthe name of a specific cartoon character.The word 'snoopy' (lower case s) is not a noun, it's an adjective used to describe a noun as offensively curious or inquisitive.
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.
It is a proper noun, because it is the name of a specific thing.
Proper noun
proper
SIM
it's a common noun. a proper noun would be Spider-Man.
Pencil proper or common noun
The noun cassette is a common noun.
a common noun?
Camel is a common noun.
The answer is proper noun. Examples of common noun and proper noun are: Proper noun: Mary Collins Common noun: monkey