What does the prefix "Kerat-" signify in medical terminology?

The prefix "Kerat-" signifies "hard" or "horny" in medical terminology, particularly in relation to the outer layer of skin or the cornea of the eye. It is derived from the Greek word "keras," meaning "horn." This prefix is commonly used in various medical terms that describe structures or conditions involving the toughness or rigidity of tissue, such as "keratin," a protein found in the skin, hair, and nails that contributes to their hard structure. Understanding this prefix helps in recognizing terms associated with protective layers or hardened tissues in the body.