Which medical term describes 'hard, horny, cornea'?

The term "kerat/o" is derived from the Greek word "kerat," which means "horn" or "cornea." This prefix is used in medical terminology to refer specifically to the cornea, which is the transparent front part of the eye that covers the iris and pupil, as well as to any structures that may have a hard, horn-like quality. In conditions such as keratitis, which is inflammation of the cornea, or keratoconus, a condition where the cornea thins and protrudes, the root "kerat/o" is fundamental to understanding the nature of these conditions related to the cornea.

The other terms do not relate to the cornea or a hard, horny structure. For instance, "keton/o" pertains to ketones, which are organic compounds that occur in the metabolism of fats; this is not related to the eye or corneal structures. "Ischi/o" refers to the ischium, which is part of the pelvis, and "jejun/o" refers to the jejunum, which is part of the small intestine. Understanding these distinctions is essential for accurate medical communication and diagnosis.