"empty diagonal" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Noms propres en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Noms propres en anglais issus d’un mot en français",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "Du français diagonale du vide."
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "name",
  "pos_title": "Nom propre",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Lexique en anglais de la géographie",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Wiktionnaire:Exemples manquants en anglais",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "diagonale du vide."
      ],
      "id": "fr-empty_diagonal-en-name-TsETEaKu",
      "topics": [
        "geography"
      ]
    }
  ],
  "word": "empty diagonal"
}

{
  "categories": [
    "Noms propres en anglais",
    "Noms propres en anglais issus d’un mot en français",
    "anglais"
  ],
  "etymology_texts": [
    "Du français diagonale du vide."
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "name",
  "pos_title": "Nom propre",
  "senses": [
    {
      "categories": [
        "Lexique en anglais de la géographie",
        "Wiktionnaire:Exemples manquants en anglais"
      ],
      "glosses": [
        "diagonale du vide."
      ],
      "topics": [
        "geography"
      ]
    }
  ],
  "word": "empty diagonal"
}