Definition of dihedrals:
(n) :
(aeronautics) The upward slope of an aircraft's wing
(adj) :
(aviation) Of wing pairs, inclined at an upward angle to each other.
(adj) :
(of a kite or an aeroplane) Having wings that form a dihedral angle, especially when the angle between the upper sides is less than 180°.
(n) :
(mathematics) An angle between two plane surfaces
(n) :
(chemistry) The angle between pairs of chemical bonds separated by a third bond
(adj) :
(mathematics) Consisting of, relating to or contained between two plane surfaces.