concussion concussion /kənˈkʌʃən/

noun

1. () Any violent blow  ( concussion )
   any violent blow
   
2. () Injury to the brain caused by a blow; usually resulting in loss of consciousness  ( concussion )
   injury to the brain caused by a blow; usually resulting in loss of consciousness
    The boxer was taken to the hospital with a concussion after being knocked out
   The boxer was taken to the hospital with a concussion after being knocked out