The brain is the most complex organ in the body, located inside the protective skull. The word can also be used as a verb in the phrase "to brain," which means to injure or kill someone by hitting them in the head.

The human brain has inspired many idioms, or colorful phrases. Thinking intently (or obsessively) about something means that you've got it "on the brain," and to "pick someone's brain" means to get their ideas on something. A puzzle is a "brainteaser, someone smart is called "a brain," and the person who runs something is said to be "the brains" of the operation.

Definitions of brain
  1. noun
    that part of the central nervous system that includes all the higher nervous centers; enclosed within the skull; continuous with the spinal cord
    synonyms: encephalon
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    type of:
    neural structure
    a structure that is part of the nervous system
  2. noun
    that which is responsible for one's thoughts and feelings; the seat of the faculty of reason
    synonyms: head, mind, nous, psyche
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    an informal British expression for head or mind
    tabula rasa
    a young mind not yet affected by experience (according to John Locke)
    (psychoanalysis) the conscious mind
    unconscious, unconscious mind
    that part of the mind wherein psychic activity takes place of which the person is unaware
    subconscious, subconscious mind
    psychic activity just below the level of awareness
    type of:
    cognition, knowledge, noesis
    the psychological result of perception and learning and reasoning
  3. noun
    mental ability
    “he's got plenty of brains but no common sense”
    synonyms: brainpower, learning ability, mental capacity, mentality, wit
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    type of:
    the ability to comprehend; to understand and profit from experience
  4. noun
    someone who has exceptional intellectual ability and originality
    synonyms: Einstein, brainiac, genius, mastermind
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    an unusually gifted or intelligent (young) person; someone whose talents excite wonder and admiration
    boy wonder
    an extremely talented young male person
    child prodigy, infant prodigy, wonder child
    a prodigy whose talents are recognized at an early age
    girl wonder
    an extremely talented young female person
    type of:
    intellect, intellectual
    a person who uses the mind creatively
  5. noun
    the brain of certain animals used as meat
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    calf's brain
    the brain of a calf eaten as meat
    type of:
    organs, variety meat
    edible viscera of a butchered animal
  6. verb
    hit on the head
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    type of:
    deal a blow to, either with the hand or with an instrument
  7. verb
    kill by smashing someone's skull
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    type of:
    cause to die; put to death, usually intentionally or knowingly
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