What is a solid bump larger than 0.4 inches (1 cm) on the skin referred to as?

A solid bump on the skin that measures larger than 0.4 inches (1 cm) is referred to as a nodule. Nodules are characterized by their firm texture and can exist deeper in the skin compared to other types of skin lesions. They may arise from a variety of skin conditions and can be located in both the epidermis and dermis layers. The size and characteristics of a nodule distinguish it from other skin lesions such as papules, which are smaller and generally do not exceed 0.4 inches. Macules are flat, colored spots on the skin without elevation, and blisters are fluid-filled sacs. The specific definition of a nodule, particularly regarding its size and structure, is what makes it the correct choice in this context.