Which term refers to a dental structure having three roots?

The term that refers to a dental structure having three roots is trifurcated. In dental terminology, "tri-" is a prefix that indicates three, so when used in conjunction with "furcated," it describes a tooth with three separate roots. This condition is often found in certain molars, which may have multiple roots to provide stability and support for the tooth's function in grinding food.

In contrast, bifurcated refers to a structure with two roots, while quadrifurcated indicates four roots. Unfurcated means there are no divisions or that the structure is a single-rooted entity. Thus, trifurcated is the correct term when specifically discussing a dental structure with three roots.