What is the opposite of wireframe?

Solution 1:

The opposite of a wireframe object is, as you've already noted, a solid object.

One might also refer to a matcap or textured object - these would normally be understood as solid although in reality they might still show the wireframe drawn over the solid face.

Another alternative (in between solid and wireframe) is a transparent object. In 3D usage that implies partial transparency of some/all of the faces allowing you to see areas of the model that wouldn't necessarily be in view in solid mode.

https://blender.stackexchange.com/questions/16339/how-to-apply-matcap-materials-for-sculpting-in-blender-2-71