Third-person singular simple present indicative form of brain

(not comparable) Having no brain. / (comparable) Unintelligent, with little common sense.

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

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

Alternative form of brainwave

(idiomatic) Obsessively in mind.

Someone who does brain surgery. / (idiomatic) Someone very intelligent.

Any of many rhythmic fluctuations of electric potential between parts of the brain, especially those seen on an electroencephalogram / A sudden idea, understanding, or inspiration; a brainstorm

impetuous and rash; hot-headed

(obsolete) an impetuous, fiery person; a hothead