scum 
/ˈskʌm/ noun
plural scums /ˈskʌm/ noun 1 [noncount] : a layer of something unpleasant or unwanted that forms on top of a liquid
▪ Boil the chicken and use a spoon to remove any scum that floats to the surface. ▪ pond scum [=a layer of algae on top of a pond] 2 informal : a dishonest, unkind, or unpleasant person [noncount] ▪ Ignore him; he's scum. ▪ They are the scum of the earth. [=the worst people on the earth] [count] ▪ He's a complete scum.
▪ Boil the chicken and use a spoon to remove any scum that floats to the surface. ▪ pond scum [=a layer of algae on top of a pond]
— scum·my /ˈskʌmi/ adjective, scum·mi·er; scum·mi·est [also more scummy; most scummy]
▪ scummy water ▪ a scummy person
/ˈskʌmi/ adjective, scum·mi·er; scum·mi·est [also more scummy; most scummy] ▪ scummy water ▪ a scummy person
