What noun is brain?

The noun "brain" can be classified as a concrete noun, meaning it refers to a physical object.

However, it can also be used as a collective noun when referring to the intellectual capacity of a person or group.

Here are some examples:

* Concrete noun: "The human brain is a complex organ." (Refers to the physical organ)

* Collective noun: "She has a sharp brain." (Refers to her intelligence)