The quality or state of being like dregs; the condition of containing sediment or being murky and unpleasant.
From 'dreggy' (adjective meaning resembling or containing dregs) plus the suffix '-ness' (which forms nouns from adjectives). The root 'dreg' comes from Old Norse 'dregg' meaning sediment or lees in a barrel of wine.
This word perfectly captures why we describe mediocre people or situations as 'dregs'—historically, wine merchants would literally have worthless sediment at the bottom of barrels, so the word became a metaphor for whatever is lowest quality and least valuable.
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