(cytology) A cell in the brain, such as a neuron or a glial cell. / (colloquial) neuron / (humorous) -- taken as a unit of intelligence

(figuratively, slang, mildly vulgar) Something ill-considered and said or done impulsively. / (figuratively, slang, mildly vulgar) An instance of absent-mindedness or forgetfulness.

Any mass educational system of improving or providing conditions to increase the intellectual quality and yield of a population of (human) brains, e.g. a university or school.

Alternative form of harebrained

Synonym of knowledge worker

(chiefly US) Originally, a group of experts who advise a government, often informally. / More recently, any group of experts assembled to give advice.

(chiefly Britain) A group of experts who discuss events in public, especially on television or radio.

impetuous and rash; hot-headed

(obsolete) an impetuous, fiery person; a hothead

Alternative form of brainwave