Before revision: Let G = (V, E) be a undirected graph and let W \subseteq V be a set of terminals. ASteiner subgraph of (G, W) is a subgraph of G that contains all vertices of W and there is a path between every pair of vertices of W in the subgraph.
After revision: Steiner subgraph of (G, W) is a subgraph of G that contains all vertices of W and there is a path between every pair of vertices of W in the subgraph.