What term is used for an injury in which part of the body is completely severed?

The term used for an injury where a part of the body is completely severed is "amputation." This refers specifically to the loss of a limb or other body part, either through surgical removal or through traumatic means, such as an accident. Amputation can happen at various levels, depending on where the severing occurred, and it results in the complete detachment of that body part from the rest of the body.

In contrast, other terms like "abrasion" refer to a type of injury involving the scraping or wearing away of the skin's surface, which does not involve severing any tissue but instead results in superficial damage. Similarly, a "contusion" is a bruise caused by blunt force, leading to bleeding under the skin without breaking the skin's surface, and a "fracture" refers to a break in a bone, which again does not imply severing of limbs or body parts. Thus, the term amputation is distinctly associated with the complete severance of a part of the body, making it the correct answer in this context.