"ℕ" meaning in Translingual

{
  "etymology_text": "The capital \"N\" is used this way in Formulario mathematico (1894) by Giuseppe Peano. The usage of blackboard bold dates to the 1960s.",
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol",
        "sc": "Zmth"
      },
      "expansion": "ℕ",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "symbol",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Translingual entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Translingual terms with non-redundant manual script codes",
          "parents": [
            "Terms with non-redundant manual script codes",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "mul",
          "name": "Mathematics",
          "orig": "mul:Mathematics",
          "parents": [
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "derived": [
        {
          "word": "ℕ₊"
        },
        {
          "word": "ℕ₀"
        }
      ],
      "glosses": [
        "The set of natural numbers, which may either include zero or not."
      ],
      "id": "en-ℕ-mul-symbol-kOP9c9xa",
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "set",
          "set"
        ],
        [
          "natural numbers",
          "natural numbers"
        ],
        [
          "zero",
          "zero"
        ]
      ],
      "raw_glosses": [
        "(mathematics) The set of natural numbers, which may either include zero or not."
      ],
      "topics": [
        "mathematics",
        "sciences"
      ],
      "wikipedia": [
        "Formulario mathematico",
        "Giuseppe Peano"
      ]
    }
  ],
  "word": "ℕ"
}

{
  "derived": [
    {
      "word": "ℕ₊"
    },
    {
      "word": "ℕ₀"
    }
  ],
  "etymology_text": "The capital \"N\" is used this way in Formulario mathematico (1894) by Giuseppe Peano. The usage of blackboard bold dates to the 1960s.",
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol",
        "sc": "Zmth"
      },
      "expansion": "ℕ",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "symbol",
  "senses": [
    {
      "categories": [
        "Translingual entries with incorrect language header",
        "Translingual lemmas",
        "Translingual symbols",
        "Translingual terms with non-redundant manual script codes",
        "mul:Mathematics"
      ],
      "glosses": [
        "The set of natural numbers, which may either include zero or not."
      ],
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "set",
          "set"
        ],
        [
          "natural numbers",
          "natural numbers"
        ],
        [
          "zero",
          "zero"
        ]
      ],
      "raw_glosses": [
        "(mathematics) The set of natural numbers, which may either include zero or not."
      ],
      "topics": [
        "mathematics",
        "sciences"
      ],
      "wikipedia": [
        "Formulario mathematico",
        "Giuseppe Peano"
      ]
    }
  ],
  "word": "ℕ"
}