A gonioscope is a medical instrument used to examine the angle where the iris meets the cornea in the eye. There are several synonyms for the term gonioscope, including goniometer, gonioscopy lens, and angle mirror. A goniometer is a device that measures the angle between two different surfaces, while a gonioscopy lens is a magnifying lens that allows for a better view of the eye's angle. An angle mirror is a specialized mirror used to reflect light and allow a clear view of the eye's angle. All of these terms refer to the same medical instrument used by ophthalmologists and optometrists to diagnose and manage conditions related to the iridocorneal angle.