"NO₂" meaning in Translingual

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol"
      },
      "expansion": "NO₂",
      "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": "topical",
          "langcode": "mul",
          "name": "Chemical formulae",
          "orig": "mul:Chemical formulae",
          "parents": [
            "Chemical notation",
            "Chemistry",
            "Names",
            "Symbols",
            "Sciences",
            "All topics",
            "Proper nouns",
            "Terms by semantic function",
            "Letters, symbols, and punctuation",
            "Fundamental",
            "Nouns",
            "Orthography",
            "Lemmas",
            "Writing",
            "Human behaviour",
            "Language",
            "Human",
            "Communication"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "In dynamic equilibrium with N₂O₄ - dinitrogen tetroxide"
        }
      ],
      "glosses": [
        "The molecular formula for nitrogen dioxide."
      ],
      "id": "en-NO₂-mul-symbol-eK2BY0k2",
      "links": [
        [
          "molecular formula",
          "molecular formula#English"
        ],
        [
          "nitrogen dioxide",
          "nitrogen dioxide#English"
        ]
      ]
    }
  ],
  "word": "NO₂"
}

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol"
      },
      "expansion": "NO₂",
      "name": "head"
    }
  ],
  "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 spelled with ₂",
        "mul:Chemical formulae"
      ],
      "examples": [
        {
          "text": "In dynamic equilibrium with N₂O₄ - dinitrogen tetroxide"
        }
      ],
      "glosses": [
        "The molecular formula for nitrogen dioxide."
      ],
      "links": [
        [
          "molecular formula",
          "molecular formula#English"
        ],
        [
          "nitrogen dioxide",
          "nitrogen dioxide#English"
        ]
      ]
    }
  ],
  "word": "NO₂"
}