"Gδ" meaning in Translingual

{
  "etymology_templates": [
    {
      "args": {
        "1": "mul",
        "2": "de",
        "3": "Gebiet",
        "4": "",
        "5": "neighborhood"
      },
      "expansion": "German Gebiet (“neighborhood”)",
      "name": "der"
    }
  ],
  "etymology_text": "From German Gebiet (“neighborhood”) for 'G' and German Durchschnitt (“intersection”) for the 'δ'.",
  "forms": [
    {
      "form": "G_δ",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol",
        "head": "G_δ"
      },
      "expansion": "G_δ",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "symbol",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Translingual entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Translingual terms written in multiple scripts",
          "parents": [
            "Terms written in multiple scripts",
            "Terms by orthographic property",
            "Terms by lexical property"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "mul",
          "name": "Mathematical analysis",
          "orig": "mul:Mathematical analysis",
          "parents": [
            "Mathematics",
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "mul",
          "name": "Measure theory",
          "orig": "mul:Measure theory",
          "parents": [
            "Mathematics",
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "mul",
          "name": "Topology",
          "orig": "mul:Topology",
          "parents": [
            "Mathematics",
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A countable intersection of open sets."
      ],
      "hypernyms": [
        {
          "word": "Borel set"
        }
      ],
      "id": "en-Gδ-mul-symbol-QN0opebi",
      "links": [
        [
          "mathematical analysis",
          "mathematical analysis"
        ],
        [
          "topology",
          "topology"
        ],
        [
          "countable",
          "countable"
        ],
        [
          "intersection",
          "intersection"
        ],
        [
          "open set",
          "open set"
        ]
      ],
      "raw_glosses": [
        "(mathematical analysis, topology) A countable intersection of open sets."
      ],
      "topics": [
        "mathematical-analysis",
        "mathematics",
        "sciences",
        "topology"
      ],
      "wikipedia": [
        "Gδ set"
      ]
    }
  ],
  "word": "Gδ"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "mul",
        "2": "de",
        "3": "Gebiet",
        "4": "",
        "5": "neighborhood"
      },
      "expansion": "German Gebiet (“neighborhood”)",
      "name": "der"
    }
  ],
  "etymology_text": "From German Gebiet (“neighborhood”) for 'G' and German Durchschnitt (“intersection”) for the 'δ'.",
  "forms": [
    {
      "form": "G_δ",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol",
        "head": "G_δ"
      },
      "expansion": "G_δ",
      "name": "head"
    }
  ],
  "hypernyms": [
    {
      "word": "Borel set"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "symbol",
  "senses": [
    {
      "categories": [
        "Pages with 1 entry",
        "Pages with entries",
        "Translingual entries with incorrect language header",
        "Translingual lemmas",
        "Translingual symbols",
        "Translingual terms derived from German",
        "Translingual terms spelled with Δ",
        "Translingual terms written in multiple scripts",
        "mul:Mathematical analysis",
        "mul:Measure theory",
        "mul:Topology"
      ],
      "glosses": [
        "A countable intersection of open sets."
      ],
      "links": [
        [
          "mathematical analysis",
          "mathematical analysis"
        ],
        [
          "topology",
          "topology"
        ],
        [
          "countable",
          "countable"
        ],
        [
          "intersection",
          "intersection"
        ],
        [
          "open set",
          "open set"
        ]
      ],
      "raw_glosses": [
        "(mathematical analysis, topology) A countable intersection of open sets."
      ],
      "topics": [
        "mathematical-analysis",
        "mathematics",
        "sciences",
        "topology"
      ],
      "wikipedia": [
        "Gδ set"
      ]
    }
  ],
  "word": "Gδ"
}