Negative First Dimension
On negative first dimension, there is no point on this space.
In abstract polytopes, the -1D shape is the null polytope; this is a consequence of abstract polytopes also being sets since the null polytope corresponds to the empty set. Some places has on it, like Cinioverse.
Negative Second Dimension
In the negative second dimension, there exists the -2D shape of the Dinull polytope. It has little physical meaning, even in the realm of abstract polytopes, but does show up in some places, such as in Cinioveres.