I. (ˈ)dī|hēdrəl adjective
Etymology: di- + -hedral
1. : having or formed by two plane faces
a dihedral angle
2.
a. of a kite or an airplane : having wings that make with one another a dihedral angle especially when the angle between the upper sides is less than 180°
b. of airplane wing pairs : inclined at a dihedral angle to each other
II. noun
( -s )
1. : a mathematical figure formed by two intersecting planes
2. : the angle between an aircraft supporting surface and a horizontal transverse line ; especially : the angle between (1) an upwardly inclined wing or (2) a downwardly inclined wing and such a line — called also respectively (1) positive dihedral or (2) negative dihedral