scum
UK[skʌm]US[skʌm]
n
A layer of unpleasant or unwanted material that forms on the surface of a liquid.
n
People considered to be worthless, dishonest, or immoral.
Etymology
The word 'scum' originates from Middle English 'scome', which referred to foam or froth. This Middle English term was borrowed from Middle Dutch 'schūm', meaning foam or froth on liquid, which itself can be traced back to Proto-Germanic 'skūmaz'. The core semantic concept has consistently been a light, frothy, or impure layer forming atop a liquid. The figurative sense, applying the idea of a worthless surface layer to describe contemptible people, developed in English by the late 16th century, demonstrating a common metaphorical extension from a physical impurity to a moral one.
Analysis
The word is a simplex form of Germanic origin. It functions as a complete lexical unit.
Examples
A layer of green scum had formed on the stagnant pond water.
He skimmed the scum off the top of the boiling soup.
The journalist wrote that the criminals were the scum of the earth.