∌
Symbol  Format  Data 

∌  Code Point 
U+220C 
TeX 
\notni 

SVG 
The does not contain as a member symbol is used in set theory to indicate that an element is not part of a set.
The contains as member symbol is used to indicate set membership in set theory.
The element of symbol indicates that an expression belongs to or is in the set.
The 'not element of' symbol is used in set theory to denote that a particular element does not belong to a specific set.