In medical terminology, what does an abrasion refer to?

An abrasion refers specifically to a scrape or a partial-thickness injury to the skin where the outer layer (epidermis) is worn away. This type of injury is often caused by friction against a rough surface, leading to the removal of the top layer of skin. Abrasions usually result in some pain and potential exposure to bacteria, which can increase the risk of infection.

In contrast, the other options do not accurately define an abrasion. Bleeding refers to the loss of blood either externally or internally, swelling indicates an increase in size of a body part due to fluid accumulation, and tenderness is a subjective sensation of pain or discomfort when pressure is applied. Each of these terms describes different aspects of injury or trauma but does not encapsulate the specific action or result of a scrape, hence the correctness of identifying an abrasion with the term meaning "scrape."