Is the word son a common noun?

No, "son" is not a common noun. It's a proper noun when referring to a specific individual, like "My son, John, is going to college."

However, "son" can be a common noun when used in a general sense, like:

* "He is the son of a famous musician."

* "The sons inherited their father's business."

In these examples, "son" refers to the general concept of a male child, not a specific individual.