Dreg

\dreg\ is a sediment that has settled at the bottom of a liquid. The residue left from the brewing process generally consisting of yeast and other solids.

Other similar words: lees (fermentation); trub (beer brewing); grounds

Dregs are mostly found at the bottom of an empty cup of tea or coffee, especially a filtered one. I just encountered this word when I took an online quiz at WizIQ.com.

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