1.(anatomy) a disk of cartilage that serves as a cushion between the ends of bones that meet at a joint • Syn: semilunar cartilage • Topics: anatomy, general anatomy • Hypernyms: cartilage, gristle 2.(optics) a lens that is concave on one side and convex on the other • Topics: optics • Hypernyms: lens, lense, lens system 3.(physics) the curved upper surface of a nonturbulent liquid in a vertical tube • Topics: physics, natural philosophy • Hypernyms: surface