Which term refers to the presence of a thickened growth on the skin's surface due to pressure or friction?

The term that refers to the presence of a thickened growth on the skin's surface due to pressure or friction is keratoma. A keratoma, often recognized as a callus or corn, develops as a protective response to repeated irritation, pressure, or friction, leading to an increase in the thickness of the outer layer of skin (epidermis). This thickening is the body's way of protecting underlying tissues from damage and is characterized by a hard or thickened surface.

On the other hand, basal cell carcinoma and squamous cell carcinoma are types of skin cancer resulting from abnormal growth of skin cells, primarily influenced by UV exposure, and they do not describe benign thickened areas due to friction or pressure. Actinic keratosis, while also a thickening of the skin, is a precancerous condition caused by sun damage, rather than being a localized adaptation to pressure or friction. Thus, keratoma is the correct term for the condition described in the question.