concussion

Concise Oxford English Dictionary © 2008 Oxford University Press:
concussion/kənˈkʌʃn/

▶noun

• 1 temporary unconsciousness or confusion caused by a blow on the head.

• 2 a violent shock as from a heavy blow.

– derivatives
concuss verb,
concussive adjective.

– origin ME: from L. concussio(n-), from concutere ‘dash together, shake’.