The cap symbol is used in mathematics as the set intersection operator. It also is used in probability to represent the occurence of two events. Typically, it is used in an expression like this:
$A∩B$
In plain language, this means the intersection of the sets $A$ and $B$. Shown below are various formats for the cap symbol.
Symbol  Format  Data 

∩  Unicode 

$∩$  TeX 

SVG 