Local Group Theory
The study of a Finite Group 
using the Local Subgroups of . Local grouptheory plays a critical role in the Classification Theorem.
- Skew Field
- Skew Lines
- Skewness
- Skew Polyomino
- Skew Quadrilateral
- Skew Symmetric Matrix
- Sklar's Theorem
- Skolem-Mahler-Lerch Theorem
- Skolem Paradox
- Skolem Sequence
- Slant Height
- Slice Knot
- Slide Move
- Slide Rule
- Slightly Defective Number
- Slightly Excessive Number
- Slip Knot
- Slope
- Slothouber-Graatsma Puzzle
- Slutzky-Yule Effect
- Sluze Pearls
- Smale-Hirsch Theorem
- Smale Horseshoe Map
- Small Cubicuboctahedron
- Small Ditrigonal Dodecacronic Hexecontahedron