scums

/S K AH1 M Z/
noun
  1. 1

    A layer of impurities that accumulates at the surface of a liquid (especially molten metal or water).

    โ€œDuring smelting, scum rises to the surface and is then removed by the smelter.โ€

  2. 2

    A greenish water vegetation (such as algae), usually found floating on the surface of ponds

    โ€œThese organisms form scum in large quantities.โ€

  3. 3

    The topmost liquid layer of a cesspool or septic tank.

  4. 4

    (chiefly US) semen

  5. 5

    A reprehensible person or persons.

    โ€œPeople who sell used-up pens are scum, just total low-lives.โ€

Source: https://en.wiktionary.org/wiki/scum, https://en.wiktionary.org/wiki/scums