Fundamental System
A set of Algebraic Invariants for a Quantic such that any invariant of the Quanticis expressible as a Polynomial in members of the set. In 1868, Gordan proved the existence of finite fundamental systemsof algebraic invariants and covariants for any binary Hilbert 
(1890) proved theHilbert Basis Theorem, which is a finiteness theorem for the related concept of Syzygies.
References
Hilbert, D. ``Über die Theorie der algebraischen Formen.'' Math. Ann. 36, 473-534, 1890.
- Smooth Manifold
- Smooth Number
- Smooth Surface
- Snake
- Snake Eyes
- Snake Oil Method
- Snake Polyiamond
- Snedecor's F-Distribution
- Snellius-Pothenot Problem
- Snowflake
- Snub Cube
- Snub Cuboctahedron
- Snub Disphenoid
- Snub Dodecadodecahedron
- Snub Dodecahedron
- Snub Icosidodecadodecahedron
- Snub Icosidodecahedron
- Snub Polyhedron
- Snub Square Antiprism
- Soap Bubble
- Soccer Ball
- Sociable Numbers
- Social Choice Theory
- Socrates' Paradox
- Soddy Circles