• Alias: un. • Infix operator with built-in evaluation rules. • xy is by default interpreted as Union[x,y]. • The character is sometimes called "cup"; but see also \[Cup] . • See also: \[Intersection] , \[SquareUnion] , \[UnionPlus] , \[Cup] , \[Vee] .
\[Union]
un
y is by default interpreted as Union[x, y]. 
is sometimes called "cup"; but see also 