Webster’s Revised Unabridged Dictionary · 1913
meniscus
me·nis′cus (·kŭs), n.; pl. L. menisci (-sī), E. Meniscuses (#). [NL., from Gr. μηνίσκος, dim. of μήνη the moon.] 1. A crescent.
2. (Opt.) A lens convex on one side and concave on the other.
3. (Anat.) An interarticular synovial cartilage or membrane; esp., one of the intervertebral synovial disks in some parts of the vertebral column of birds.
Converging meniscus, Diverging meniscus. See Lens.