Source : Webster's Revised Unabridged Dictionary (1913)
Dihedral \Di*he"dral\, a.
1. 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].
2. (A["e]ronautics) Of wing pairs, inclined at an upward
angle to each other.
Dihedral \Di*he"dral\, a. [Gr. di- = di`s- 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.