Di‐he″dral (?), a. [Gr. δι- = δίσ- twice + � a seat, bottom, base, fr. � to sit. Cf. Diedral.] Having two plane faces; as, the dihedral summit of a crystal.
Dihedral angle, the angular space contained between planes which intersect. It is measured by the angle made by any two lines at right angles to the two planes.