"tretti" meaning in Norwegian Bokmål

{
  "etymology_templates": [
    {
      "args": {
        "1": "nb",
        "2": "non",
        "3": "þrír tigir"
      },
      "expansion": "Old Norse þrír tigir",
      "name": "der"
    },
    {
      "args": {
        "1": "nb",
        "2": "tredve"
      },
      "expansion": "tredve",
      "name": "m"
    }
  ],
  "etymology_text": "From Old Norse þrír tigir, also from older form tredve (as in Danish).",
  "head_templates": [
    {
      "args": {
        "1": "nb",
        "2": "numeral"
      },
      "expansion": "tretti",
      "name": "head"
    }
  ],
  "lang": "Norwegian Bokmål",
  "lang_code": "nb",
  "pos": "num",
  "senses": [
    {
      "categories": [
        {
          "kind": "topical",
          "name": "Norwegian Bokmål cardinal numbers",
          "parents": [
            "Cardinal numbers",
            "Numbers",
            "All topics",
            "Terms by semantic function",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Norwegian Bokmål entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "thirty"
      ],
      "id": "en-tretti-nb-num-rKX7Wdtp",
      "links": [
        [
          "thirty",
          "thirty#English"
        ]
      ],
      "related": [
        {
          "word": "trettiende"
        }
      ],
      "synonyms": [
        {
          "tags": [
            "Riksmål"
          ],
          "word": "tredve"
        }
      ]
    }
  ],
  "word": "tretti"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "nb",
        "2": "non",
        "3": "þrír tigir"
      },
      "expansion": "Old Norse þrír tigir",
      "name": "der"
    },
    {
      "args": {
        "1": "nb",
        "2": "tredve"
      },
      "expansion": "tredve",
      "name": "m"
    }
  ],
  "etymology_text": "From Old Norse þrír tigir, also from older form tredve (as in Danish).",
  "head_templates": [
    {
      "args": {
        "1": "nb",
        "2": "numeral"
      },
      "expansion": "tretti",
      "name": "head"
    }
  ],
  "lang": "Norwegian Bokmål",
  "lang_code": "nb",
  "pos": "num",
  "related": [
    {
      "word": "trettiende"
    }
  ],
  "senses": [
    {
      "categories": [
        "Norwegian Bokmål cardinal numbers",
        "Norwegian Bokmål entries with incorrect language header",
        "Norwegian Bokmål lemmas",
        "Norwegian Bokmål numerals",
        "Norwegian Bokmål terms derived from Old Norse"
      ],
      "glosses": [
        "thirty"
      ],
      "links": [
        [
          "thirty",
          "thirty#English"
        ]
      ]
    }
  ],
  "synonyms": [
    {
      "tags": [
        "Riksmål"
      ],
      "word": "tredve"
    }
  ],
  "word": "tretti"
}