Dihedral or polyhedral may refer to:
- Dihedral angle, the angle between two mathematical planes
- Dihedral (aircraft), the upward angle of a fixed-wing aircraft's wings where they meet at the fuselage, dihedral effect of an aircraft, longitudinal dihedral angle of a fixed-wing aircraft
- Dihedral group, the group of symmetries of the n-sided polygon in abstract algebra
- Also Dihedral symmetry in three dimensions
- Dihedral kite, also known as a bowed kite
- Dihedral doors, also known as butterfly doors
- Dihedral prime, also known as a dihedral calculator prime
- An inside corner of rock; see the glossary of climbing terms