An Etymological Dictionary of Astronomy and Astrophysics

A generally reddish matter that settles from a liquid, especially from wine.
Same as → tartar.

Etymology (EN): M.E. argul, argoile, from M.Fr. argoil, from L. argilla “argil.”

Etymology (PE): Lerd ou lert “the sediment of liquids, dregs, lees” (Dehxodâ).