What does anhedral mean?
Anhedral is a technical noun with two established uses. In aeronautics, it describes the downward slope of an aircraft's wings away from the horizontal — the opposite of dihedral, where wings tilt upward. Designers build anhedral into high-wing aircraft to prevent them from being excessively stable in roll, allowing smoother handling; military jets like the Harrier display it strikingly. In crystallography, anhedral characterizes minerals that lack well-formed external faces, so their grains show irregular boundaries rather than the flat planes typical of euhedral crystals. The word derives from Greek roots meaning 'without a seat or face,' sharing ancestry with terms like polyhedron and cathedral. Though confined largely to engineering and geological literature, anhedral is a precise, useful term for anyone reading about aircraft design or rock-forming minerals, and it pairs naturally with its antonym dihedral in both fields.
nounThe downward inclination of an aircraft's wings relative to the horizontal plane, the opposite of dihedral; also, in crystallography, the property of a mineral lacking well-formed external crystal faces.
- (Aeronautics) The downward angle of an aircraft's wings from the horizontal, opposite of dihedral, typically used to enhance roll stability in high-wing aircraft.
- (Crystallography) The condition of a mineral occurring without distinct, well-developed external crystal faces.
"The fighter jet's pronounced anhedral gave it a distinctive, aggressive stance on the tarmac."
"High-wing aircraft such as the C-5 Galaxy employ noticeable anhedral to counteract excessive rolling stability."
"Under the microscope, the quartz grains proved entirely anhedral, with no trace of their original crystal outlines."
Rarely pluralized; usually treated as an uncountable technical property, though 'anhedrals' can appear when comparing different aircraft designs.
"Comparing the anhedrals of various high-wing transports reveals how designers balance stability and agility."
Look at a Harrier jump jet or an F-104 Starfighter: those downward-sloping wings aren't drooping from fatigue — that's anhedral, and it's there on purpose to keep the plane stable.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of anhedral
Anhedral comes from the Greek root 'hedra,' meaning 'seat' or 'face,' combined with the negative prefix 'an-' (from Greek 'anō,' without). It entered English through scientific Latin usage alongside related terms such as dihedral and polyhedral, all built on the same root that also gives us 'cathedral' (from 'cathedra,' a seat). Its adoption in both aeronautical and crystallographic vocabulary reflects nineteenth- and twentieth-century scientific naming conventions drawing on classical Greek.
How anhedral is actually used
Primarily a technical term used by aerospace engineers, pilots, and geologists; rarely encountered in general conversation. In aviation contexts it is often discussed alongside its opposite, dihedral, and sometimes called 'negative dihedral.'
Easily confused with anhedral
Anhedonia is the psychological inability to feel pleasure, whereas anhedral refers to a downward-angled aircraft wing configuration or a mineral's lack of crystal faces.