Is "aunt" a proper noun?
The noun "aunt" (lower case a) is a common noun as a general word for a sister of your mother or your father.
The noun "Aunt" (capital A) is a proper noun as the title of a specific person.
I'll be visiting my aunt over the summer. (common noun)
I'll be visiting my Aunt Mary over the summer. (proper noun)
John's aunt sent him a check for his birthday. (common noun)
John's Aunt Mary sent him a check for his birthday. (proper noun)