Final answer:
A third-degree burn is referred to as a full-thickness burn and requires medical attention due to the severity of tissue damage.
Step-by-step explanation:
A third-degree burn is also known as a full-thickness burn. This level of burn fully extends into both the epidermis and dermis, destroying the tissue and affecting nerve endings and sensory function. These burns require immediate medical attention and are serious because they can result in white, red, or blackened skin and heal slowly, potentially leading to significant scarring or the need for skin grafts.