"うんん" meaning in Japanese

{
  "forms": [
    {
      "form": "unn",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "interjection"
      },
      "expansion": "うんん • (unn)",
      "name": "ja-pos"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "intj",
  "senses": [
    {
      "alt_of": [
        {
          "word": "ううん"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "Japanese entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Japanese links with redundant wikilinks",
          "parents": [
            "Links with redundant wikilinks",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Japanese terms with redundant sortkeys",
          "parents": [
            "Terms with redundant sortkeys",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Alternative spelling of ううん"
      ],
      "id": "en-うんん-ja-intj-ZrvQyJq-",
      "links": [
        [
          "ううん",
          "ううん#Japanese"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "うんん"
}

{
  "forms": [
    {
      "form": "unn",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "interjection"
      },
      "expansion": "うんん • (unn)",
      "name": "ja-pos"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "intj",
  "senses": [
    {
      "alt_of": [
        {
          "word": "ううん"
        }
      ],
      "categories": [
        "Japanese entries with incorrect language header",
        "Japanese hiragana",
        "Japanese interjections",
        "Japanese lemmas",
        "Japanese links with redundant wikilinks",
        "Japanese terms with redundant sortkeys",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "Alternative spelling of ううん"
      ],
      "links": [
        [
          "ううん",
          "ううん#Japanese"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "うんん"
}

{
  "called_from": "parser/1336",
  "msg": "no corresponding start tag found for </span>",
  "path": [
    "うんん"
  ],
  "section": "Japanese",
  "subsection": "interjection",
  "title": "うんん",
  "trace": ""
}