Skeleton[n] represents a sequence of n omitted elements in an expression printed with Short or Shallow. The standard print form for Skeleton is <<n>>.
Skip
(Built-in Mathematica Symbol) Skip[stream, type] skips one object of the specified type in an input stream. Skip[stream, type, n] skips n objects of the specified type.
Spacings is an option to Grid and related constructs that specifies the spacings to leave between successive objects.
SplineDegree is an option for spline functions and graphics primitives that specifies the degree of polynomial basis to use.
StackBegin[expr] evaluates expr, starting a fresh evaluation stack.
StringTrim["string"] trims whitespace from the beginning and end of " string".StringTrim["string", patt] trims substrings matching patt from the beginning and end.
SubMinus[expr] displays as expr_-.
SubPlus
(Built-in Mathematica Symbol) SubPlus[expr] displays as expr_+.
Superscript[x, y] is an object that formats as x^y.
SymbolName[symbol] gives the name of the specified symbol.