Baby is a common noun. Proper nouns are the unique names of people, places, or things. Common nouns are the words for general things. If a common noun is part of a name, it becomes a proper noun. Pronouns always replace proper and common nouns.
By itself, it is a common noun. If it is the name of a specific one, then it is a proper noun.
There is a monument in Paris. (monument is common, Paris is proper)
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
common noun, it is not specific to one person or thing
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.