Brain

Anatomy, Zoology. the part of the central nervous system enclosed in the cranium of humans and other vertebrates, consisting of a soft, convoluted mass of gray and white matter and serving to control and coordinate the mental and physical actions.
Zoology. (in many invertebrates) a part of the nervous system more or less corresponding to the brain of vertebrates.
Sometimes, brains. (used with a plural verb) understanding; intellectual power; intelligence.
the brain as the center of thought, understanding, etc.; mind; intellect.
brains, Slang. a member of a group who is regarded as its intellectual leader or planner:
The junior partner is the brains of the firm.
Informal. a very intelligent or brilliant person.
Informal.

the controlling or guiding mechanism in a computer, robot, pacemaker, etc.
the part of a computer system for coordination or guidance, as of a missile.

to smash the skull of.
Slang. to hit or bang (someone) on the head.
beat one’s brains out, Informal. to try very hard to understand and work out a problem, remember something, etc.:
She beat her brains out studying for the exam.
have something on the brain, to have an obsession; be occupied with:
Lately I seem to have food on the brain.
pick someone’s brains, to obtain information by questioning another person rather than by seeking it independently:
He refused to prepare for the exam but counted on being able to pick his roommate’s brains.
Contemporary Examples

The Evolution of Darwin and Lincoln The Daily Beast February 2, 2009
The Science Community’s Fight Over an Artificial Brain Elizabeth Picciuto July 9, 2014
Patton Oswalt Sounds Off On Stand-Up’s Critics and Why Comedians Should Win Oscars Marlow Stern December 26, 2013
Scott Walker Beats Recall, Wins in WI Howard Kurtz June 5, 2012
Why Do We Cry? Michael Trimble January 9, 2013

Historical Examples

The Destroyer Burton Egbert Stevenson
Way of the Lawless Max Brand
The Education of Henry Adams Henry Adams
Weighed and Wanting George MacDonald
Unwise Child Gordon Randall Garrett

noun
the soft convoluted mass of nervous tissue within the skull of vertebrates that is the controlling and coordinating centre of the nervous system and the seat of thought, memory, and emotion. It includes the cerebrum, brainstem, and cerebellum Technical name encephalon, related adjectives cerebral encephalic
the main neural bundle or ganglion of certain invertebrates
(often pl) (informal) intellectual ability: he’s got brains
(informal) shrewdness or cunning
(informal) an intellectual or intelligent person
(usually pl; functioning as singular) (informal) a person who plans and organizes an undertaking or is in overall control of an organization, etc
an electronic device, such as a computer, that performs apparently similar functions to the human brain
on the brain, constantly in mind: I had that song on the brain
pick someone’s brain, to obtain information or ideas from someone
verb (transitive)
to smash the skull of
(slang) to hit hard on the head
n.
v.
brain
(brān)

brain drain
brain someone
brain trust