Sludge

Part of speech: noun

Pronunciation: /slʌd͡ʒ/

Definitions

1. A viscous and often foul-smelling mixture of sediment, typically resulting from industrial processes, that can also refer to accumulated deposits in aquatic environments
2. A heavy, mucky substance resulting from the combination of liquid waste with particulate matter, which can settle in tanks or natural bodies of water
3. A dense, muddy substance formed from a mixture of water and solid particles often associated with waste ; the layer of accumulated solids that settles during cleaning of water or sewage

Etymology: Sludge began as a word for mud itself, and its lineage runs back to Proto-Germanic "slikiz", which meant mud or slush. Old English had "sliċ", a word for mire or sticky earth, and in Middle English the root branched into a family of related forms, including "sliche" and "slicche", which covered mud, slush and even tar. Modern English "slitch" is a surviving relative of that older branch. The word that became "sludge" probably came from an alteration of these Middle English forms, most likely "slugge" or "sluche", which meant mud or mire. Over time the sense narrowed away from clean-ish wet earth toward the murky, heavy waste we associate with it now. Its cousins sit across the North Sea: Dutch "slijk" and German "Schlick" both keep the same muddy sense. English "slush" is a close relation too, sharing the same sticky, watery world of wet, unpleasant ground.

Synonyms: muck, mud, silt, sediment, waste

Antonyms: cleanliness, purity, clarity, freshness, tidiness