Forms Data Controls :: Binding Web Service Result Into Gridview/Data Source Is An Invalid Type

I having problem binding web service result into a gridview. I using Word Dictionary Web Service for my project. Below is part of my code.

Web References I using is :

[URL]

Protected void Button1_Click(object sender,
EventArgs e) {
DictService ds = new DictService();
ds.DefineAsync(TextBox1.Text);
ds.DefineCompleted += new DefineCompletedEventHandler(ds_DefineCompleted); }
void ds_DefineCompleted(object sender, DefineCompletedEventArgs e){
GridView1.DataSource = e.Result;
GridView1.DataBind();}

The Error i get is : Data source is an invalid type. It must be either an IListSource, IEnumerable, or IDataSource.