Involution (Group)
An element of order 2 in a Group (i.e., an element 
of a Group such that 
, where 
is theIdentity Element).
- Steenrod's Realization Problem
- Steepest Descent Method
- Steffensen's Inequality
- Steffenson's Formula
- Steinbach Screw
- Steiner Chain
- Steiner Construction
- Steinerian Curve
- Steiner-Lehmus Theorem
- Steiner Points
- Steiner Quadruple System
- Steiner's Ellipse
- Steiner Set
- Steiner's Hypocycloid
- Steiner's Porism
- Steiner's Problem
- Steiner's Segment Problem
- Steiner's Theorem
- Steiner Surface
- Steiner System
- Steiner Triple System
- Steinhaus-Moser Notation
- Steinitz's Theorem
- Steinmetz Solid
- Stella Octangula