'Dihedral angle' definitions:

Definition of 'Dihedral angle'

From: GCIDE

Dihedral \Di*he"dral\, a. [Gr. di- = di`s- twice + ? a seat, bottom, base, fr. ? to sit. Cf. Diedral.]
1. Having two plane faces; as, the dihedral summit of a crystal. [1913 Webster]
2. Of a kite or an a["e]roplane, having wings that make with one another a dihedral angle, esp. when the angle between the upper sides is less than 180[deg]. [Webster 1913 Suppl.]
3. (A["e]ronautics) Of wing pairs, inclined at an upward angle to each other. [Webster 1913 Suppl.]
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. [1913 Webster]