1. past tense of scum; formed a layer of froth or foam on the surface
2. past tense of scum; removed scum or impurities from the surface of a liquid

Examples

• The pond had scummed over with algae during the hot summer.
• The cook scummed the broth to remove impurities.
• Green algae scummed the surface of the stagnant water.
• She carefully scummed the soup before serving it.
• The old well had scummed with debris and leaves.
• The chef scummed the stock pot every few minutes.