The noun "brain" represents the control center of the central nervous system responsible for various mental functions and abilities.

(informal) A noun "brain" represents an intelligent person or a person who provides the intelligence required for something.

(in the plural) A noun "brain" represents the intellectual or mental capacity.

By analogy with a human brain, the part of a machine or computer that performs calculations.

(slang, vulgar, uncountable) Oral sex.

(informal, slang) Mind.

A loose compartment of a backpack that straps on over the top opening.

(transitive) To dash out the brains of; to kill by smashing the skull.

(transitive, slang) To strike (someone) on the head.

(transitive, figurative) To destroy; to put an end to.