meniscus

/M EH0 N IH1 S K AH0 S/
noun
  1. 1

    A crescent moon, or an object shaped like it.

  2. 2

    A lens which is convex on one side and concave on the other, being crescent-shaped in cross-section.

  3. 3

    The curved surface of liquids in tubes, whether concave or convex, caused by the surface tension of the liquid.

  4. 4

    Either of two parts of the human knee that provide structural integrity to the knee when it undergoes tension and torsion.

Source: https://en.wiktionary.org/wiki/meniscus