|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
in Roman times, an artificial reservoir used for swimming or as a fish pond. During the Middle Ages a piscina was a pool or tank in which fish were stored by monastic communities, for whose members fish was a staple item of diet.
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