"Borel set" meaning in English

{
  "etymology_text": "Named after Émile Borel.",
  "forms": [
    {
      "form": "Borel sets",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Borel set (plural Borel sets)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "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 entries with topic categories using raw markup",
          "parents": [
            "Entries with topic 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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Mathematical analysis",
          "orig": "en:Mathematical analysis",
          "parents": [
            "Mathematics",
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Measure theory",
          "orig": "en:Measure theory",
          "parents": [
            "Mathematics",
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "A Lebesgue measurable set is expressible as a union of a Borel set and a Lebesgue null set.",
          "type": "example"
        }
      ],
      "glosses": [
        "Any of the members of a Borel σ-algebra."
      ],
      "holonyms": [
        {
          "word": "Borel σ-algebra"
        }
      ],
      "hyponyms": [
        {
          "word": "Fσ"
        },
        {
          "word": "Gδ"
        }
      ],
      "id": "en-Borel_set-en-noun-9dNeCZHO",
      "links": [
        [
          "mathematical analysis",
          "mathematical analysis"
        ],
        [
          "Borel σ-algebra",
          "Borel σ-algebra"
        ]
      ],
      "raw_glosses": [
        "(mathematical analysis) Any of the members of a Borel σ-algebra."
      ],
      "related": [
        {
          "word": "borelian"
        }
      ],
      "topics": [
        "mathematical-analysis",
        "mathematics",
        "sciences"
      ],
      "translations": [
        {
          "code": "fi",
          "lang": "Finnish",
          "sense": "Translations",
          "word": "Borel-joukko"
        },
        {
          "code": "de",
          "lang": "German",
          "sense": "Translations",
          "tags": [
            "feminine"
          ],
          "word": "Borel-Menge"
        },
        {
          "code": "de",
          "lang": "German",
          "sense": "Translations",
          "tags": [
            "feminine"
          ],
          "word": "Borelsche Menge"
        },
        {
          "code": "pl",
          "lang": "Polish",
          "sense": "Translations",
          "tags": [
            "masculine"
          ],
          "word": "zbiór borelowski"
        }
      ],
      "wikipedia": [
        "Borel set",
        "Émile Borel"
      ]
    }
  ],
  "word": "Borel set"
}

{
  "etymology_text": "Named after Émile Borel.",
  "forms": [
    {
      "form": "Borel sets",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Borel set (plural Borel sets)",
      "name": "en-noun"
    }
  ],
  "holonyms": [
    {
      "word": "Borel σ-algebra"
    }
  ],
  "hyponyms": [
    {
      "word": "Fσ"
    },
    {
      "word": "Gδ"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "borelian"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English entries with topic categories using raw markup",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys",
        "English terms with usage examples",
        "Translation table header lacks gloss",
        "en:Mathematical analysis",
        "en:Measure theory"
      ],
      "examples": [
        {
          "text": "A Lebesgue measurable set is expressible as a union of a Borel set and a Lebesgue null set.",
          "type": "example"
        }
      ],
      "glosses": [
        "Any of the members of a Borel σ-algebra."
      ],
      "links": [
        [
          "mathematical analysis",
          "mathematical analysis"
        ],
        [
          "Borel σ-algebra",
          "Borel σ-algebra"
        ]
      ],
      "raw_glosses": [
        "(mathematical analysis) Any of the members of a Borel σ-algebra."
      ],
      "topics": [
        "mathematical-analysis",
        "mathematics",
        "sciences"
      ],
      "wikipedia": [
        "Borel set",
        "Émile Borel"
      ]
    }
  ],
  "translations": [
    {
      "code": "fi",
      "lang": "Finnish",
      "sense": "Translations",
      "word": "Borel-joukko"
    },
    {
      "code": "de",
      "lang": "German",
      "sense": "Translations",
      "tags": [
        "feminine"
      ],
      "word": "Borel-Menge"
    },
    {
      "code": "de",
      "lang": "German",
      "sense": "Translations",
      "tags": [
        "feminine"
      ],
      "word": "Borelsche Menge"
    },
    {
      "code": "pl",
      "lang": "Polish",
      "sense": "Translations",
      "tags": [
        "masculine"
      ],
      "word": "zbiór borelowski"
    }
  ],
  "word": "Borel set"
}