What condition would best describe a bruise under the skin?

A bruise under the skin is best described as a contusion. This condition occurs when small blood vessels near the surface of the skin break due to trauma, causing blood to leak into the surrounding tissue. The accumulation of blood leads to the characteristic discoloration that we recognize as a bruise, which can change colors as the body breaks down the pooled blood over time.

In contrast, laceration refers to a tear or cut in the skin, which typically involves a break in the skin's integrity, and would not result in the same type of discoloration as a bruise. An avulsion is a more severe type of injury where a portion of skin or tissue is forcibly detached from the body, and an incision describes a clean-cut wound typically made with a sharp object, which also does not relate to the underlying mechanism of a bruise. Thus, the specific nature of a contusion directly corresponds to the situation of having a bruise under the skin.