\begin{table}%t7
\caption{\label{defo2hd}Definitions in the [$W_0({\rm OII})$, $W_0(\rm H_{\delta})$] plane.}
%\centering
\small
\begin{tabular}{c c c}
\hline \hline
Definition & $W_0(\rm OII)$ & $W_0(\rm H_{\delta})$ \\
\hline
PEV (passive) & ${<}4.85$ & ${\leq}5$ \\
SF (star-forming) & ${\geq}4.85$ & $\in$[0, 5] \\
SSB (short starburst) & ${\geq}4.85$ & ${<}0$ \\
\hline
\end{tabular}
\end{table}