RuntimeOptions is an option for Compile that specifies runtime settings for the compiled function it creates.
ScheduledTaskObject[id, expr, spec, ...] is a task object specifying future evaluation of expr according to spec.
ScriptSizeMultipliers is an option for Style that specifies how much smaller to render each successive level of subscripts, etc.
Selectable is an option for displayed objects, cells, and notebooks that specifies whether their contents can be selected interactively using the front end.
ShowAutoStyles is an option for Cell that specifies whether styles that are specified to be automatically used for various syntactic and other constructs should be shown.
ShowCellLabel is an option for Cell that specifies whether to display the label for a cell.
Sign
(Built-in Mathematica Symbol) Sign[x] gives -1, 0, or 1 depending on whether x is negative, zero, or positive.
SlideView[{expr_1, expr_2, ...}] represents an object in which the expr_i are set up to be displayed on successive slides. SlideView[{expr_1, expr_2, ...}, i] makes the ...
Sqrt
(Built-in Mathematica Symbol) Sqrt[z] or Sqrt[z] gives the square root of z.
SubMinus[expr] displays as expr_-.