Kite
A planar convex quadrilateral consisting of two adjacent sides of length 
and the other two sides of length 
. TheRhombus is a special case of the kite, and the Lozenge is a special case of the Rhombus.
- Salesman Problem
- Salient Point
- Salinon
- Salmon's Theorem
- Saltus
- Sample Proportion
- Sample Space
- Sample Variance
- Sampling
- Sampling Function
- Sampling Theorem
- Sandwich Theorem
- San Marco Fractal
- Sard's Theorem
- Sarkovskii's Theorem
- Sarrus Linkage
- Sarrus Number
- SAS Theorem
- Satellite Knot
- Satisfiability Problem
- Sausage Conjecture
- Savitzky-Golay Filter
- Savoy Knot
- Scalar
- Scalar Curvature