"šťastnou" meaning in Czech

{
  "etymology_templates": [
    {
      "args": {
        "1": "cs",
        "2": "štěstí",
        "3": "ou"
      },
      "expansion": "štěstí + -ou",
      "name": "suffix"
    }
  ],
  "etymology_text": "štěstí + -ou",
  "head_templates": [
    {
      "args": {
        "1": "cs",
        "2": "adjective form"
      },
      "expansion": "šťastnou",
      "name": "head"
    }
  ],
  "lang": "Czech",
  "lang_code": "cs",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Czech entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Czech terms suffixed with -ou",
          "parents": [],
          "source": "w"
        }
      ],
      "form_of": [
        {
          "word": "šťastný"
        }
      ],
      "glosses": [
        "feminine accusative/instrumental singular of šťastný"
      ],
      "id": "en-šťastnou-cs-adj-gkDkv6WR",
      "links": [
        [
          "šťastný",
          "šťastný#Czech"
        ]
      ],
      "tags": [
        "accusative",
        "feminine",
        "form-of",
        "instrumental",
        "singular"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈʃcastnou̯]"
    }
  ],
  "word": "šťastnou"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "cs",
        "2": "štěstí",
        "3": "ou"
      },
      "expansion": "štěstí + -ou",
      "name": "suffix"
    }
  ],
  "etymology_text": "štěstí + -ou",
  "head_templates": [
    {
      "args": {
        "1": "cs",
        "2": "adjective form"
      },
      "expansion": "šťastnou",
      "name": "head"
    }
  ],
  "lang": "Czech",
  "lang_code": "cs",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        "Czech adjective forms",
        "Czech entries with incorrect language header",
        "Czech non-lemma forms",
        "Czech terms suffixed with -ou",
        "Czech terms with IPA pronunciation"
      ],
      "form_of": [
        {
          "word": "šťastný"
        }
      ],
      "glosses": [
        "feminine accusative/instrumental singular of šťastný"
      ],
      "links": [
        [
          "šťastný",
          "šťastný#Czech"
        ]
      ],
      "tags": [
        "accusative",
        "feminine",
        "form-of",
        "instrumental",
        "singular"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[ˈʃcastnou̯]"
    }
  ],
  "word": "šťastnou"
}