Typo fix.

src/topology/main/regular.tex

@@ -6,7 +6,7 @@
     Let $X$ be a topological space, then the following are equivalent:
     \begin{enumerate}
         \item For each $x \in X$ and $A \subset X$ closed with $x \not\in A$, there exists $U \in \cn(x)$ and $V \in \cn(A)$ such that $U \cap V = \emptyset$.
-        \item For each $x \in X$, the closed neighbourhoods of $x$ forms a fundamantal system of neighbourhoods at $x$.
+        \item For each $x \in X$, the closed neighbourhoods of $x$ forms a fundamental system of neighbourhoods at $x$.
     \end{enumerate}
     If $X$ is a T1 space such that the above holds, then $X$ is \textbf{regular}.
 \end{definition}