US is not a word, it's an abbreviation. United States is the proper noun.
The noun 'Ohio' is a proper noun, the name of a state in the US; the name of a specific place. A proper noun is always capitalized.A common noun is a general word for a person, place, or thing. A common noun for the proper noun 'Ohio' is state.
As it is the name for a specific thing, it is a proper noun.
The noun 'route' is a common noun, for example, This is the route to Boston. Any common noun becomes a proper noun when it is used for a specific person, place, thing, or a title such as US Route 66 or the TV show 'Route 66'.
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
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?
A common noun is a word for any person, place, or thing. A proper noun is is the name of a person, place, thing, or a title. common noun: boy proper noun: 'The Blue Boy', painting by Thomas Gainsborough common noun: cruise proper noun: Tom Cruise, actor common noun: bush proper noun: George H.W. Bush and George W. Bush, US Presidents common noun: palm proper noun: Palm Beach, FL common noun: lakes proper noun: Land O' Lakes, WI and Land O' Lakes butter common noun: china proper noun: People's Republic of China common noun: dairy proper noun: Dairy Queen common noun: apple proper noun: Apple, Inc., Cupertino, CA common noun: bridge proper noun: Golden Gate Bridge common noun: state proper noun: US Department of State common noun: war proper noun: 'War and Peace' by Leo Tolstoy common noun: friends proper noun: 'Friends' TV series 1994-2004