"Hajnal line" meaning in English

{
  "etymology_text": "Proposed in 1965 by John Hajnal.",
  "forms": [
    {
      "form": "the Hajnal line",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "def": "1"
      },
      "expansion": "the Hajnal line",
      "name": "en-prop"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "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 entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "An imaginary line drawn between Saint Petersburg in Russia and Trieste in Italy, sometimes thought to divide Europe into two areas characterized by different levels of nuptiality, with lower marriage and fertility rates to the west, and higher rates to the east."
      ],
      "id": "en-Hajnal_line-en-name-9NpVG1Nj",
      "links": [
        [
          "Saint Petersburg",
          "Saint Petersburg"
        ],
        [
          "Russia",
          "Russia"
        ],
        [
          "Trieste",
          "Trieste"
        ],
        [
          "Italy",
          "Italy"
        ],
        [
          "divide",
          "divide"
        ],
        [
          "Europe",
          "Europe"
        ],
        [
          "nuptiality",
          "nuptiality"
        ]
      ],
      "wikipedia": [
        "John Hajnal"
      ]
    }
  ],
  "word": "Hajnal line"
}

{
  "etymology_text": "Proposed in 1965 by John Hajnal.",
  "forms": [
    {
      "form": "the Hajnal line",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "def": "1"
      },
      "expansion": "the Hajnal line",
      "name": "en-prop"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English proper nouns",
        "English terms with non-redundant non-automated sortkeys",
        "English uncountable nouns"
      ],
      "glosses": [
        "An imaginary line drawn between Saint Petersburg in Russia and Trieste in Italy, sometimes thought to divide Europe into two areas characterized by different levels of nuptiality, with lower marriage and fertility rates to the west, and higher rates to the east."
      ],
      "links": [
        [
          "Saint Petersburg",
          "Saint Petersburg"
        ],
        [
          "Russia",
          "Russia"
        ],
        [
          "Trieste",
          "Trieste"
        ],
        [
          "Italy",
          "Italy"
        ],
        [
          "divide",
          "divide"
        ],
        [
          "Europe",
          "Europe"
        ],
        [
          "nuptiality",
          "nuptiality"
        ]
      ],
      "wikipedia": [
        "John Hajnal"
      ]
    }
  ],
  "word": "Hajnal line"
}