dihedral

adjective

1. having or formed by two intersecting plane faces: a dihedral angle
2. 1. having wings that form a dihedral angle with each other, as some airplanes
   2. being inclined to each other at a dihedral angle: said of airplane wing pairs

noun

1. a dihedral angle
2. the acute angle, normally upward, between the wings of certain airplanes, designed to improve lateral stability