Or contusion; Patch of discoloration on the skin resulting from seepage of blood from damaged underlying vessels. It is caused by injury, usually a blow. The change in color of a bruise is due to degradation of hemoglobin in the tissues.An injury that doesn't break the skin but results in some discoloration; SYN. contusion.

ETYM Latin contusio: cf. French contusion.
1. The act or process of beating, bruising, or pounding; the state of being beaten or bruised.
2. A bruise; an injury attended with more or less disorganization of the subcutaneous tissue and effusion of blood beneath the skin, but without apparent wound.