Regulus
The locus of lines meeting three given Skew Lines. (``Regulus'' is also the name of the brighteststar 
in the constellation Leo.)
- Surjection
- Surjective
- Surprise Examination Paradox
- Surreal Number
- Surrogate
- Surveying Problems
- Survivorship Curve
- Suslin's Theorem
- Suspended Knot
- Suspension
- Suzanne Set
- Suzuki Group
- Swallowtail Catastrophe
- Swastika
- Swastika Curve
- Sweep Signal
- Swinnerton-Dyer Conjecture
- Swinnerton-Dyer Polynomial
- Swirl
- Sylow p-Subgroup
- Sylow Theorems
- Sylvester Cyclotomic Number
- Sylvester Graph
- Sylvester Matrix
- Sylvester's Determinant Identity