English definition of “brain”
ORGAN [C] › the organ inside your head that controls your thoughts, feelings, and movements: brain damage
PERSON [C] informal › an extremely intelligent person: [usually plural] This university attracts some of the best brains in the country.
brains › intelligence: He has brains and good looks.
have sth on the brain informal › to think or talk about something all the time: You've got football on the brain!
the brains behind sth informal › the person who has planned and organized something successful: Anthony is the brains behind the project.