An Etymological Dictionary of the German Language/Annotated/Schaum
Schaum, masculine, ‘foam, froth, scum,’ from the equivalent Middle High German schûm, Old High German scûm, m,; corresponding; to Dutch schuim, Old Icelandic skúm, ‘foam’ (whence English scum). The other dialects have a different word; compare Anglo-Saxon fám, English foam, under Feim. It is questionable whether Latin spuma, ‘foam’ (with p for k, compare lupus with λύκος?), is connected with the Teutonic cognates. Schaum is usually connected with the root skû, ‘to cover,’ appearing in Scheuer; hence it means literally ‘covering, that which covers.’ From Teutonic are derived Italian schiuma, French écume, ‘foam.’