The Collaborative International Dictionary
Contrecoup
Contrecoup \Con`tre*coup"\, n. [F., fr. contre (L. contra) + coup a blow.] (med.) A concussion or shock produced by a blow or other injury, in a part or region opposite to that at which the blow is received, often causing rupture or disorganisation of the parts affected.
Wiktionary
contrecoup
n. (context pathology English) A bruising of the brain caused by a blow, appearing on the opposite side to that on which the blow was struck.