"cardinal vowel" meaning in English

{
  "etymology_text": "The term was coined by the British phoneticians Daniel Jones in the early 20th century.",
  "forms": [
    {
      "form": "cardinal vowels",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "cardinal vowel (plural cardinal vowels)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Entries with translation boxes",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Polish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Phonetics",
          "orig": "en:Phonetics",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "a vowel sound produced when the tongue is in an extreme position, either front or back, high or low."
      ],
      "id": "en-cardinal_vowel-en-noun-ALK39TiI",
      "links": [
        [
          "phonetics",
          "phonetics"
        ],
        [
          "vowel",
          "vowel"
        ]
      ],
      "raw_glosses": [
        "(phonetics) a vowel sound produced when the tongue is in an extreme position, either front or back, high or low."
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "phonetics",
        "phonology",
        "sciences"
      ],
      "translations": [
        {
          "code": "pl",
          "lang": "Polish",
          "lang_code": "pl",
          "sense": "any vowel sound produced in the front of the mouth",
          "tags": [
            "feminine"
          ],
          "word": "samogłoska kardynalna"
        },
        {
          "code": "pl",
          "lang": "Polish",
          "lang_code": "pl",
          "sense": "any vowel sound produced in the front of the mouth",
          "tags": [
            "feminine"
          ],
          "word": "samogłoska podstawowa"
        }
      ],
      "wikipedia": [
        "Daniel Jones (phonetician)"
      ]
    }
  ],
  "word": "cardinal vowel"
}

{
  "etymology_text": "The term was coined by the British phoneticians Daniel Jones in the early 20th century.",
  "forms": [
    {
      "form": "cardinal vowels",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "cardinal vowel (plural cardinal vowels)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Entries with translation boxes",
        "Pages with 1 entry",
        "Pages with entries",
        "Terms with Polish translations",
        "en:Phonetics"
      ],
      "glosses": [
        "a vowel sound produced when the tongue is in an extreme position, either front or back, high or low."
      ],
      "links": [
        [
          "phonetics",
          "phonetics"
        ],
        [
          "vowel",
          "vowel"
        ]
      ],
      "raw_glosses": [
        "(phonetics) a vowel sound produced when the tongue is in an extreme position, either front or back, high or low."
      ],
      "topics": [
        "human-sciences",
        "linguistics",
        "phonetics",
        "phonology",
        "sciences"
      ],
      "wikipedia": [
        "Daniel Jones (phonetician)"
      ]
    }
  ],
  "translations": [
    {
      "code": "pl",
      "lang": "Polish",
      "lang_code": "pl",
      "sense": "any vowel sound produced in the front of the mouth",
      "tags": [
        "feminine"
      ],
      "word": "samogłoska kardynalna"
    },
    {
      "code": "pl",
      "lang": "Polish",
      "lang_code": "pl",
      "sense": "any vowel sound produced in the front of the mouth",
      "tags": [
        "feminine"
      ],
      "word": "samogłoska podstawowa"
    }
  ],
  "word": "cardinal vowel"
}