SpellingDictionariesPath is a global option that specifies which directories are searched for spelling dictionaries when the Edit \[FilledRightTriangle] Check Spelling menu ...
SphericalBesselY[n, z] gives the spherical Bessel function of the second kind y_n (z).
SphericalHankelH2[n, z] gives the spherical Hankel function of the second kind h_n^(2)(z).
SquareIntersection[x, y, ...] displays as x \[SquareIntersection] y \[SquareIntersection] ....
SquareSubset[x, y, ...] displays as x \[SquareSubset] y \[SquareSubset] ....
SquareSuperset[x, y, ...] displays as x \[SquareSuperset] y \[SquareSuperset] ....
SquareUnion[x, y, ...] displays as x \[SquareUnion] y \[SquareUnion] ....
Star
(Built-in Mathematica Symbol) Star[x, y, ...] displays as x\[Star]y\[Star]....
StructuredSelection is an option for Cell that specifies whether to allow only complete subexpressions in the cell to be selected interactively using the front end.
StyleNameDialogSettings -> {opt -> val} is a global option that specifies the cell style displayed in the Custom Style dialog box.