- singular tangential plane
- singular term
- singular theory
- singular torus
- singular transformation
- singular value
- singular value decomposition
- singular variational problem
- singular variety
- singular vector
- singular zero
- sinhc function (= hyperbolic sine cardinal function)
- sinh-Gordon equation
- sinh (= hyperbolic sine)
- sinh-Poisson equation
- sinistrorse curve
- sinistrorse helix
- sinistrorse ruled surface
- sinistrorsum curve
- sink
- sink of a mapping
- sink of a network
- sink of a tree
- sink of a vector field
- sink strength