"diagonal principal" meaning in Spanish

{
  "forms": [
    {
      "form": "diagonales principales",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "diagonal principal f (plural diagonales principales)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
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          "kind": "other",
          "name": "Pages with 2 entries",
          "parents": [],
          "source": "w"
        },
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          "kind": "other",
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          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Spanish entries with incorrect language header",
          "parents": [
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            "Entry maintenance"
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          "source": "w"
        },
        {
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          "langcode": "es",
          "name": "Linear algebra",
          "orig": "es:Linear algebra",
          "parents": [
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            "Mathematics",
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      ],
      "glosses": [
        "main diagonal"
      ],
      "id": "en-diagonal_principal-es-noun-A-xtgfBo",
      "links": [
        [
          "linear algebra",
          "linear algebra"
        ],
        [
          "main diagonal",
          "main diagonal"
        ]
      ],
      "raw_glosses": [
        "(linear algebra) main diagonal"
      ],
      "tags": [
        "feminine"
      ],
      "topics": [
        "linear-algebra",
        "mathematics",
        "sciences"
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  ],
  "word": "diagonal principal"
}

{
  "forms": [
    {
      "form": "diagonales principales",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "diagonal principal f (plural diagonales principales)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
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        "es:Linear algebra"
      ],
      "glosses": [
        "main diagonal"
      ],
      "links": [
        [
          "linear algebra",
          "linear algebra"
        ],
        [
          "main diagonal",
          "main diagonal"
        ]
      ],
      "raw_glosses": [
        "(linear algebra) main diagonal"
      ],
      "tags": [
        "feminine"
      ],
      "topics": [
        "linear-algebra",
        "mathematics",
        "sciences"
      ]
    }
  ],
  "word": "diagonal principal"
}