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brain

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noun British English pronunciation: brain /breɪn/ 
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singularbrain
pluralbrains
  1. 1
    [countable] the organ inside your head that allows you to think and feel, and controls your body

    The human brain is divided into two halves.

    The illness had affected his brain.

    1. a.
      [only before noun] belonging to or connected with the brain

      a brain tumour/scan/operation

      brain activity/function

  2. 2
    [countable] [often plural] mental ability or intelligence

    She felt that she could almost see his brain working.

    You have to use your brains in this job.

    have brains/a brain (=be intelligent):

    He's good-looking, and he's got brains.

    1. a.
      [countable] an intelligent person

      The best brains in the country have failed to solve this problem.

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