Suppose \(X_1,\ldots ,X_n\) are topological spaces and \(p_i\in X_i\). Then
\begin{equation*} X_1\vee \cdots \vee X_n:= X_1 \coprod \cdots \coprod X_n/\{p_1,\ldots ,p_n\} \end{equation*}is called wedge sum of \(X_1,\ldots ,X_n\). One can imagine that \(X_1\) up to \(X_n\) are glued together.