Final answer:
A third-degree burn is a severe burn that fully extends into the epidermis and dermis, destroying the tissue and affecting the nerve endings and sensory function.
Step-by-step explanation:
A third-degree burn is a severe burn that fully extends into the epidermis and dermis, destroying the tissue and affecting the nerve endings and sensory function. These burns may appear white, red, or black and require medical attention. Unlike first-degree and second-degree burns, third-degree burns are usually not as painful because the nerve endings themselves are damaged.