Which of the following terms also refers to the 'eye or vision'?

The term "ophthalm/o" is derived from the Greek word "ophthalmos," which specifically means 'eye' or 'vision.' It is commonly used in medical terminology related to the eyes and vision, forming the basis for various terms such as ophthalmology (the study of the eye and its diseases) and ophthalmologist (a medical doctor specializing in eye care and surgery). This designation makes it clear that "ophthalm/o" directly relates to the eye or vision, establishing it as the correct choice in the context of this question.

In contrast, the other terms refer to different body parts or systems: "or/o" pertains to the mouth, "orchid/o" relates to the testicles (from the Greek word "orchis"), and "onc/o" is associated with tumors or cancer. Each of these terms has its own specific medical connotations that do not overlap with eye or vision references.