Rodrigues's Curvature Formula
where
is the unit Normal Vector and 
is one of the two Principal Curvatures.See also Normal Vector, Principal Curvatures- Steffenson's Formula
- Steinbach Screw
- Steiner Chain
- Steiner Construction
- Steinerian Curve
- Steiner-Lehmus Theorem
- Steiner Points
- Steiner Quadruple System
- Steiner's Ellipse
- Steiner Set
- Steiner's Hypocycloid
- Steiner's Porism
- Steiner's Problem
- Steiner's Segment Problem
- Steiner's Theorem
- Steiner Surface
- Steiner System
- Steiner Triple System
- Steinhaus-Moser Notation
- Steinitz's Theorem
- Steinmetz Solid
- Stella Octangula
- Stella Octangula Number
- Stellated Polyhedron
- Stellated Tetrahedron