• (n.) Coagulated sour milk; loppered milk; curdled milk; -- sometimes called simply clabber.
Bon'ny·clab`ber noun [ Ir. bainne , baine , milk + clabar mud, mire.] Coagulated sour milk; loppered milk; curdled milk; -- sometimes called simply clabber . B. Jonson. 
Bonnyclabber is a drink made from beer and buttermilk.
clabber (def. 1).