\[ShortRightArrow] (Mathematica Character Name)

Unicode: F525. x  y is by default interpreted as ShortRightArrow[x,y]. Infix arrow operator. Not the same as \[Rule]. Extensible character.

\[Sigma] (Mathematica Character Name)

Unicode: 03C3. Aliases: Esc s Esc, Esc sigma Esc. Greek letter. Used in TraditionalForm for DivisorSigma and WeierstrassSigma.

\[SixPointedStar] (Mathematica Character Name)

Unicode: 2736. Alias: Esc *6 Esc. Letter-like form. Not the same as the operator \[Star].

\[SkeletonIndicator] (Mathematica Character Name)

Unicode: 2043. Uninterpretable element. ⁃ name ⁃ is used on output to indicate an expression that has head name, but whose arguments will not explicitly be given. ...

\[SpaceIndicator] (Mathematica Character Name)

Unicode: 2423. Alias: Esc space Esc. Spacing character. Interpreted by default as equivalent to \[RawSpace].

\[SphericalAngle] (Mathematica Character Name)

Unicode: 2222. Letter-like form. Used in geometry to indicate a spherical angle, as in the symbol ∢ ABC.

\[Sqrt] (Mathematica Character Name)

Unicode: 221A. Alias: Esc sqrt Esc. Prefix operator with built-in evaluation rules. √ x is by default interpreted as Sqrt[x]. Ctrl+@, Ctrl+2 or ∖@ yields a complete SqrtBox ...

\[SquareIntersection] (Mathematica Character Name)

Unicode: 2293. Infix operator. x ⊓ y is by default interpreted as SquareIntersection[x,y].

\[Square] (Mathematica Character Name)

Unicode: F520. Alias: Esc sq Esc. Prefix operator.  x is by default interpreted as Square[x]. Used in mathematical physics to denote the d'Alembertian operator. Sometimes ...

\[SquareSubsetEqual] (Mathematica Character Name)

Unicode: 2291. Infix set relation operator. x ⊑ y is by default interpreted as SquareSubsetEqual[x,y].