Final answer:
A circumscribed flat nonpalpable change in skin color is known as a macule, which is a smooth spot of discoloration on the skin.
Step-by-step explanation:
A circumscribed flat nonpalpable change in skin color is known as a macule. This term is typically used to describe smooth spots of discoloration on the skin that are not raised above the skin's surface. Whereas a macule refers to flat discoloration, a papule is a small raised bump on the skin, petechiae are small red or purple spots from blood leaking out of vessels, and ecchymosis is a larger area of skin discoloration due to bleeding underneath.