Faces are a term used in Geometry to describe a side on a three-dimensional figure
A solid is a 3 dimensional object in terms of math.
Proprioception is the medical term meaning three-dimensional perception.
Having three sides.
Trompe L'oeil, maybe, though it's not really related to the Math, Algebra, Geometry category.
They are solid shapes as for example a pyramid
Solid shaper: ones that have a length, width and depth.