Trihedron
A Triple of three arbitrary vectors with common vertex. The vectors are often taken to beunit vectors, and the term trihedron is perhaps most commonly encountered in the consideration of the unit OrthogonalVectors given by 
, 
, and 
(Tangent Vector, Normal Vector, and BinormalVector).
- Sturmian Sequence
- Sturm-Liouville Equation
- Sturm-Liouville Theory
- Sturm Theorem
- Stäckel Determinant
- Stérmer Number
- Stöhr Sequence
- Subalgebra
- Subanalytic
- Subfactorial
- Subfield
- Subgraph
- Subgroup
- Sublime Number
- Submanifold
- Submatrix
- Subnormal
- Subordinate Norm
- Subscript
- Subsequence
- Subset
- Subspace
- Substitution Group
- Substitution Map
- Subtend