Wound, a break in the continuity of any bodily tissue due to violence, where violence is understood to encompass any action of external agency, including, for example, surgery. The most important distinction is between open and closed wounds. Open wounds are those in which the protective body surface (the skin or mucous membranes) has been broken, permitting the entry of foreign material into the tissues. In closed wounds, by contrast, the damaged tissues are not exposed to the exterior, and the process of repair can take place without the interference that contamination brings, in greater or lesser degree.

Ulcers are wounds or open sores that will not heal or keep returning. Ulcers can appear anywhere in or on your body, from the lining in your stomach to the outer layer of your skin.

Sometimes ulcers disappear on their own. Other times they require medical treatment to prevent serious complications.

A wound is caused by an external force whereas an ulcer is caused by an internal problem. In a wound, the primary tissue breakdown is caused by a force originating from the external world and the disturbance of the tissue will typically be acute. In an ulcer, the primary tissue breakdown is internal, i.e. the lesion is caused by an underlying disease or other internal reason. This disturbance of the tissue will typically be gradual.