PlayRange is an option for Play and related functions which specifies what range of sound amplitude levels should be included.
PlotRange is an option for graphics functions that specifies what range of coordinates to include in a plot.
RecordLists is an option for ReadList that specifies whether objects from separate records should be returned in separate sublists.
ReverseGraph[g] gives the reverse graph of the directed g.
RiemannSiegelZ[t] gives the Riemann\[Dash]Siegel function Z(t).
RootReduce[expr] attempts to reduce expr to a single Root object.
SampledSoundList[{a_1, a_2, ...}, r] is a sound primitive that represents a sound whose amplitude has levels a_i sampled r times a second.
ScheduledTaskObject[id, expr, spec, ...] is a task object specifying future evaluation of expr according to spec.
Sharpen
(Built-in Mathematica Symbol) Sharpen[image] gives a sharpened version of image.Sharpen[image, r] gives a version of image sharpened over pixel radius r.
ShowCellLabel is an option for Cell that specifies whether to display the label for a cell.