the.com/suds

means The foamy mass of bubbles that forms when soap or detergent mixes with water and air.

from 'Suds' traces back to Middle English 'sudden' or related forms tied to seething and boiling — itself from Old English/Germanic roots meaning to seethe, boil, or simmer (a cousin of the word 'seethe' itself). The idea is of liquid agitated into a frothy, bubbling state, which is exactly what suds are: water worked up into a lather. The word settled into its soapy, domestic sense by the time washing laundry became a word-worthy chore.