D defs.my
Entry 3 senses Webster, 1913

Dihedral

· Di·he·dral · IPA /daɪˈhiːdɹəl/
01 a. Having two plane faces; as, the dihedral summit of a crystal.
  1. 1.
    Having two plane faces; as, the dihedral summit of a crystal.
  2. 2.
    Of a kite or an aëroplane, having wings that make with one another a dihedral angle, esp. when the angle between the upper sides is less than 180°.
  3. 3.
    Of wing pairs, inclined at an upward angle to each other.(Aëronautics)
Phrases & compounds
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.