Screw
A Translation along a straight line 
and a Rotation about such that the angle of Rotation isproportional to the Translation at each instant. Also known as a Twist.
- Simpson's 3/8 Rule
- Simpson's Paradox
- Simpson's Rule
- Simson Line
- Sinc Function
- Sinclair's Soap Film Problem
- Sine
- Sine-Gordon Equation
- Sine Integral
- Sines Law
- Sine-Tangent Theorem
- Singly Even Number
- Singular Homology
- Singularity
- Singular Point (Algebraic Curve)
- Singular Point (Differential Equation)
- Singular Point (Function)
- Singular Series
- Singular System
- Singular Value
- Singular Value Decomposition
- Sinh
- Sink (Directed Graph)
- Sink (Map)
- Sinusoidal Projection