What term refers to an arc that is smaller than a semicircle?

The term that refers to an arc smaller than a semicircle is "minor." In the context of a circle, an arc is a section of the circumference. If an arc measures less than 180 degrees, it is classified as a minor arc. This specific definition differentiates it from a major arc, which measures more than 180 degrees and represents the larger section of the circle's circumference.

The other terms listed do not relate to arcs in a circular context. "Median" typically refers to a middle value in a set of numbers, "major" describes arcs larger than a semicircle, and "mean" is another statistical term that signifies the average value. Thus, recognizing that the characteristic of being smaller than a semicircle aligns distinctly with the label "minor" clarifies why this option is the appropriate choice.