1. A filmy or frothy layer of matter that forms on the surface of a liquid or body of water or on a hard surface.
2. The refuse or dross of molten metals.
3. Refuse or worthless matter.
4. Slang One, such as a person or an element of society, that is regarded as despicable or worthless.
v. scummed, scum·ming, scums
To remove the scum from.
To become covered with scum.
[Middle English, from Middle Dutch schūm; see (s)keu- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.