interplanar
Interplanar is an adjective used to describe relationships, measurements, or structures that occur between planes. It is widely applied in physics, chemistry, and geometry to distinguish what lies between two or more planes from what exists within a single plane (intraplanar).
In crystallography, interplanar spacing, denoted d, is the perpendicular distance between two parallel crystallographic planes. Planes
In geometry and materials science, the concept extends to angles between planes (dihedral angles) and to properties
Usage is technical and contextual; the term is almost exclusively encountered in scientific literature and discussions