An Etymological Dictionary of the German Language/Schaum
Schaum, m., ‘foam, froth, scum,’ from the equiv. MidHG. schûm, OHG. scûm, m,; corresponding; to Du. schuim, OIc. skúm, ‘foam’ (whence E. scum). The other dials. have a different word; comp. AS. fám, E. foam, under Feim. It is questionable whether Lat. spuma, ‘foam’ (with p for k, comp. lupus with λύκος?), is connected with the Teut. cognates. Schaum is usually connected with the root skû, ‘to cover,’ appearing in Scheuer; hence it means lit. ‘covering, that which covers.’ From Teut. are derived Ital. schiuma, Fr. écume, ‘foam.’