biconcave

/baɪˈkɑnkeɪv/
adjective
  1. Curved inward on both sides, like a lens or a red blood cell.
    • The biconcave lens spreads light rays apart.
    • The scientist examined the biconcave structure of the tiny fossil under a microscope.
    • Red blood cells have a biconcave shape that helps them carry oxygen.
Antonyms
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