[OS X TeX] label too wide

[George Gratzer]

I need this:

\begin{enumerate}
\item[(Refl)]%P1
Reflexivity\index{Reflexivity}\index{Binary relation!reflexive}:\hspace{21pt} $a 
\leq a$.\hfill 
\item[(Asym)]%P2
\index{Asym}\index{Binary relation!antisymmetric} Antisymmetry:\q $a 
\leq b$ and $b \leq a$ imply that $a = b$.
\item[(Trans)]%P3
Transitivity\index{Transitivity}\index{Binary relation!transitive}:\hspace{17pt} 
$a \leq b$ and $b \leq c$ imply that $a \leq c$. 
\item[(Lin)]%P4
Linearity\index{Linearity}:\hspace{29pt} $a \leq b$ or $b \leq a$. 
\end{enumerate}

The problem is that the labels are too wide, stick out to the margin. Bow to fix it?

GG