Common Noun:
* When "twin" refers to one individual who is part of a pair born at the same time, it is a common noun.
* Example: "The twin was born with a birthmark on his arm."
Collective Noun:
* When "twin" refers to the pair of individuals born at the same time, it is a collective noun.
* Example: "The twins are celebrating their birthday today."
Here's a breakdown:
* Common noun: Refers to a general person, place, or thing.
* Collective noun: Refers to a group of people or things considered as one unit.
Therefore, "twin" can be both a common noun and a collective noun, depending on the context of its use.