anhedral
1 of 2adjective
an·he·dral
(ˈ)an-¦hē-drəl
: allotriomorphic
anhedral
2 of 2noun
an·he·dral (ˈ)an-¦hē-drəl 
plural anhedrals
aeronautics
: the angle between a downwardly inclined aircraft wing and a horizontal transverse line
The bottom wing had pronounced anhedral; the upper wing, dihedral.
William Hallstead, Air & Space/Smithsonian, Feb/Mar 2000
William Hallstead, Air & Space/Smithsonian, Feb/Mar 2000called also negative dihedral
Word History
Etymology
Adjective
an- + -hedral
Noun
an- + (di)hedral
First Known Use
Adjective
1896, in the meaning defined above
Noun
circa 1956, in the meaning defined above