"biconcave" meaning in English

{
  "antonyms": [
    {
      "word": "biconvex"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "bi",
        "3": "concave"
      },
      "expansion": "bi- + concave",
      "name": "prefix"
    }
  ],
  "etymology_text": "bi- + concave",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "biconcave (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms prefixed with bi-",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Anatomy",
          "orig": "en:Anatomy",
          "parents": [
            "Biology",
            "Medicine",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Optics",
          "orig": "en:Optics",
          "parents": [
            "Physics",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "a biconcave lens"
        },
        {
          "text": "the biconcave vertebrae"
        },
        {
          "text": "Red blood cells are biconcave."
        }
      ],
      "glosses": [
        "Having both sides concave"
      ],
      "id": "en-biconcave-en-adj-9LFxmX-d",
      "links": [
        [
          "optics",
          "optics"
        ],
        [
          "anatomy",
          "anatomy"
        ],
        [
          "concave",
          "concave"
        ]
      ],
      "raw_glosses": [
        "(optics, anatomy) Having both sides concave"
      ],
      "synonyms": [
        {
          "word": "concave"
        },
        {
          "word": "concavoconcave"
        }
      ],
      "tags": [
        "not-comparable"
      ],
      "topics": [
        "anatomy",
        "engineering",
        "medicine",
        "natural-sciences",
        "optics",
        "physical-sciences",
        "physics",
        "sciences"
      ],
      "translations": [
        {
          "code": "fr",
          "lang": "French",
          "sense": "lens",
          "tags": [
            "feminine",
            "masculine"
          ],
          "word": "biconcave"
        },
        {
          "code": "el",
          "lang": "Greek",
          "roman": "amfíkoilos",
          "sense": "lens",
          "word": "αμφίκοιλος"
        },
        {
          "code": "it",
          "lang": "Italian",
          "sense": "lens",
          "tags": [
            "masculine"
          ],
          "word": "biconcavo"
        },
        {
          "code": "fa",
          "lang": "Persian",
          "roman": "dokâv",
          "sense": "lens",
          "word": "دوکاو"
        }
      ]
    }
  ],
  "word": "biconcave"
}

{
  "antonyms": [
    {
      "word": "biconvex"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "bi",
        "3": "concave"
      },
      "expansion": "bi- + concave",
      "name": "prefix"
    }
  ],
  "etymology_text": "bi- + concave",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "biconcave (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        "English adjectives",
        "English entries with incorrect language header",
        "English lemmas",
        "English terms prefixed with bi-",
        "English uncomparable adjectives",
        "en:Anatomy",
        "en:Optics"
      ],
      "examples": [
        {
          "text": "a biconcave lens"
        },
        {
          "text": "the biconcave vertebrae"
        },
        {
          "text": "Red blood cells are biconcave."
        }
      ],
      "glosses": [
        "Having both sides concave"
      ],
      "links": [
        [
          "optics",
          "optics"
        ],
        [
          "anatomy",
          "anatomy"
        ],
        [
          "concave",
          "concave"
        ]
      ],
      "raw_glosses": [
        "(optics, anatomy) Having both sides concave"
      ],
      "tags": [
        "not-comparable"
      ],
      "topics": [
        "anatomy",
        "engineering",
        "medicine",
        "natural-sciences",
        "optics",
        "physical-sciences",
        "physics",
        "sciences"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "concave"
    },
    {
      "word": "concavoconcave"
    }
  ],
  "translations": [
    {
      "code": "fr",
      "lang": "French",
      "sense": "lens",
      "tags": [
        "feminine",
        "masculine"
      ],
      "word": "biconcave"
    },
    {
      "code": "el",
      "lang": "Greek",
      "roman": "amfíkoilos",
      "sense": "lens",
      "word": "αμφίκοιλος"
    },
    {
      "code": "it",
      "lang": "Italian",
      "sense": "lens",
      "tags": [
        "masculine"
      ],
      "word": "biconcavo"
    },
    {
      "code": "fa",
      "lang": "Persian",
      "roman": "dokâv",
      "sense": "lens",
      "word": "دوکاو"
    }
  ],
  "word": "biconcave"
}