Irrotational Field
A Vector Field 
for which the Curl vanishes,
See also Beltrami Field, Conservative Field, Solenoidal Field, Vector Field
- Spencer's 15-Point Moving Average
- Spence's Function
- Spence's Integral
- Sperner's Theorem
- Sphenocorona
- Sphenoid
- Sphenomegacorona
- Sphere
- Sphere-Cylinder Intersection
- Sphere Embedding
- Sphere Eversion
- Sphere Geodesic
- Sphere Packing
- Sphere Point Picking
- Sphere-Sphere Intersection
- Sphere with Tunnel
- Spherical Bessel Differential Equation
- Spherical Bessel Function
- Spherical Bessel Function of the First Kind
- Spherical Bessel Function of the Second Kind
- Spherical Bessel Function of the Third Kind
- Spherical Cap
- Spherical Coordinates
- Spherical Design
- Spherical Excess