meniscus

From Ancient Greek μηνίσκος (mēnískos, “crescent”), from μήνη (mḗnē, “moon”)

• (UK, US) IPA^(key): /mɛˈnɪs.kəs/, /məˈnɪs.kəs/

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meniscus (plural meniscuses or menisci)

1. A crescent moon, or an object shaped like it. [from 17th c.]
   • 1972, Vladimir Nabokov, Transparent Things, McGraw-Hill 1972, p. 19:

     He opened wide both casements; they gave on a parking place four floors below; the thin meniscus overhead was too wan to illumine the roofs of the houses descending toward the invisible lake [...].

2. (optics) A lens which is convex on one side and concave on the other, being crescent-shaped in cross-section. [from 17th c.]
3. The curved surface of liquids in tubes, whether concave or convex, caused by the surface tension of the liquid. [from 19th c.]
4. (anatomy) Either of two parts of the human knee that provide structural integrity to the knee when it undergoes tension and torsion. [from 19th c.]

• lunette