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.