Definition of concussion noun from the Oxford Advanced Learner's Dictionary

 

concussion

 noun
noun
BrE BrE//kənˈkʌʃn//
 
; NAmE NAmE//kənˈkʌʃn//
 
[uncountable] Injuries
 
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(This word is only [C] in NAmE.) a temporary loss of consciousness caused by a blow to the head; the effects of a severe blow to the head such as confusion and temporary loss of physical and mental abilities (British English) He was taken to hospital with concussion. (North American English) He was taken to the hospital with a concussion. He was carried off the field with a mild concussion. She suffered mild concussion. See related entries: Injuries Word Origin late Middle English: from Latin concussio(n-), from the verb concutere ‘dash together, shake’, from con- ‘together’ + quatere ‘shake’.
See the Oxford Advanced American Dictionary entry: concussion