A logical operator denoting nonexistence or indicating that no element satisfying a given condition exists.
Examples
Basic statement of non-existence
\nexists x \in \mathbb{R} : x^2 < 0
Set theory negation
\nexists n \in \mathbb{N} : n^2 = 2
Complex logical statement
\nexists x \in \mathbb{Z} : (x > 0 \land x < 1)