1. noun /bɹeɪn/
a) The control center of the central nervous system of an animal located in the skull which is responsible for perception, cognition, attention, memory, emotion, and action.
He was a total brain.
b) An intelligent person.
He is the brains behind the scheme.
2. verb /bɹeɪn/
a) To strike (someone) on the head.
b) To kill (a person) by smashing that persons skull.
Wikipedia foundation.