scum

kuona

roskaväki, pohjasakka

irrottaa kuonaa puhekieltä A layer of impurity impurities that accumulates at the surface of a liquid (especially molten metal or water).
puhekieltä A greenish water vegetation (such as algae), usually found floating on the surface of ponds
The topmost liquid layer of a cesspool or septic tank.
puhekieltä semen
puhekieltä A reprehensible person or persons.
To remove the layer of scum from (a liquid etc.).
To remove (something) as scum.
1590, Edmund Spenser, The Faerie Queene, II.vii:

Some scumd the drosse, that from the metall came; / Some stird the molten owre with ladles great(nb..).

Take the smallest Cucumbers you can get, and as free from Spots as possible, put them into a strong Salt and Water for nine or ten Days, or 'till they are quite Yellow, and stir them twice a Day at least, or they will scum over, and grow soft

SOo by Merlyns aduys ther were sente fore rydars to skumme the Countreye / & they mette with the fore rydars of the north / and made hem to telle whiche wey the hooste cam / and thenne they told it to Arthur / and by kyng Ban and Bors counceill they lete brenne and destroye alle the contrey afore them there they shold ryde

Wandering up and down without certain seat, they lived by scumming those seas and shores as pirates.

A great majority of the members are scummed together from the Jacobinical dregs of former periods of the revolution.