"hen's tooth" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "horsefeathers"
      },
      "expansion": "horsefeathers",
      "name": "m"
    },
    {
      "args": {
        "1": "en",
        "2": "when pigs fly"
      },
      "expansion": "when pigs fly",
      "name": "m"
    }
  ],
  "etymology_text": "Example of a jocularly non-existent phenomenon, as many birds lack any teeth (having developed a bill instead). Compare horsefeathers and when pigs fly.",
  "forms": [
    {
      "form": "hen's teeth",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "hens' teeth",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "hen's teeth",
        "2": "hens' teeth"
      },
      "expansion": "hen's tooth (plural hen's teeth or hens' teeth)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "as rare as a hen's tooth"
        }
      ],
      "glosses": [
        "anything not naturally occurring"
      ],
      "id": "en-hen's_tooth-en-noun-KvtpG3za",
      "raw_glosses": [
        "(idiomatic) anything not naturally occurring"
      ],
      "related": [
        {
          "word": "unobtanium"
        }
      ],
      "synonyms": [
        {
          "word": "rocking horse shit"
        },
        {
          "word": "rarity"
        }
      ],
      "tags": [
        "idiomatic"
      ],
      "translations": [
        {
          "code": "ru",
          "lang": "Russian",
          "roman": "ptíčʹje molokó",
          "sense": "something rare or hard to find",
          "word": "пти́чье молоко́"
        }
      ]
    }
  ],
  "sounds": [
    {
      "audio": "en-au-hen's tooth.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/c/cd/En-au-hen%27s_tooth.ogg/En-au-hen%27s_tooth.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/c/cd/En-au-hen%27s_tooth.ogg",
      "tags": [
        "Australia"
      ],
      "text": "Audio (AU)"
    }
  ],
  "word": "hen's tooth"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "horsefeathers"
      },
      "expansion": "horsefeathers",
      "name": "m"
    },
    {
      "args": {
        "1": "en",
        "2": "when pigs fly"
      },
      "expansion": "when pigs fly",
      "name": "m"
    }
  ],
  "etymology_text": "Example of a jocularly non-existent phenomenon, as many birds lack any teeth (having developed a bill instead). Compare horsefeathers and when pigs fly.",
  "forms": [
    {
      "form": "hen's teeth",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "hens' teeth",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "hen's teeth",
        "2": "hens' teeth"
      },
      "expansion": "hen's tooth (plural hen's teeth or hens' teeth)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "unobtanium"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English idioms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with audio links"
      ],
      "examples": [
        {
          "text": "as rare as a hen's tooth"
        }
      ],
      "glosses": [
        "anything not naturally occurring"
      ],
      "raw_glosses": [
        "(idiomatic) anything not naturally occurring"
      ],
      "tags": [
        "idiomatic"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "en-au-hen's tooth.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/c/cd/En-au-hen%27s_tooth.ogg/En-au-hen%27s_tooth.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/c/cd/En-au-hen%27s_tooth.ogg",
      "tags": [
        "Australia"
      ],
      "text": "Audio (AU)"
    }
  ],
  "synonyms": [
    {
      "word": "rocking horse shit"
    },
    {
      "word": "rarity"
    }
  ],
  "translations": [
    {
      "code": "ru",
      "lang": "Russian",
      "roman": "ptíčʹje molokó",
      "sense": "something rare or hard to find",
      "word": "пти́чье молоко́"
    }
  ],
  "word": "hen's tooth"
}