TildeTilde[x, y, ...] displays as x \[TildeTilde] y \[TildeTilde] ....
TitsGroupT[] represents the simple Tits group T.
UnionPlus[x, y, ...] displays as x \[UnionPlus] y \[UnionPlus] ....
UnsavedVariables is an option for Manipulate, DynamicModule, and related functions that specifies local symbols that should not be saved when the notebook containing them is ...
UpArrowBar[x, y, ...] displays as x\[UpArrowBar]y\[UpArrowBar]....
UpArrowDownArrow[x, y, ...] displays as x\[UpArrowDownArrow]y\[UpArrowDownArrow]....
UpArrow
(Built-in Mathematica Symbol) UpArrow[x, y, ...] displays as x\[UpArrow]y\[UpArrow]TraditionalForm\`....
UpDownArrow[x, y, ...] displays as x\[UpDownArrow]y\[UpDownArrow]....
UpEquilibrium[x, y, ...] displays as x\[UpEquilibrium]y\[UpEquilibrium]....
UpperLeftArrow[x, y, ...] displays as x \[UpperLeftArrow] y \[UpperLeftArrow] ....