"doubtful" meaning in English

{
  "categories": [
    {
      "kind": "other",
      "name": "Terms suffixed with -ful",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "doubt",
        "2": "ful"
      },
      "expansion": "doubt + -ful",
      "name": "ety-suffix"
    }
  ],
  "etymology_text": "doubt + -ful",
  "forms": [
    {
      "form": "doubtful",
      "tags": [
        "positive"
      ]
    },
    {
      "form": "more doubtful",
      "tags": [
        "comparative"
      ]
    },
    {
      "form": "most doubtful",
      "tags": [
        "superlative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "more": "true"
      },
      "expansion": "[POS TABLE]",
      "name": "adj"
    }
  ],
  "hyphenation": "doubt‧ful",
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "examples": [
        {
          "text": "The fool made many doubtful claims."
        }
      ],
      "glosses": [
        "If something is doubtful it is probably not true."
      ],
      "id": "simple-doubtful-en-adj-gYo0pBgS",
      "synonyms": [
        {
          "word": "dubious"
        }
      ]
    },
    {
      "examples": [
        {
          "text": "The teacher was doubtful of his bad students."
        }
      ],
      "glosses": [
        "If someone is doubtful they are doubting something or someone."
      ],
      "id": "simple-doubtful-en-adj-ROpK~SJq"
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈdaʊtfəl/"
    },
    {
      "audio": "en-us-doubtful.ogg",
      "tags": [
        "US"
      ]
    }
  ],
  "word": "doubtful"
}

{
  "categories": [
    "Terms suffixed with -ful"
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "doubt",
        "2": "ful"
      },
      "expansion": "doubt + -ful",
      "name": "ety-suffix"
    }
  ],
  "etymology_text": "doubt + -ful",
  "forms": [
    {
      "form": "doubtful",
      "tags": [
        "positive"
      ]
    },
    {
      "form": "more doubtful",
      "tags": [
        "comparative"
      ]
    },
    {
      "form": "most doubtful",
      "tags": [
        "superlative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "more": "true"
      },
      "expansion": "[POS TABLE]",
      "name": "adj"
    }
  ],
  "hyphenation": "doubt‧ful",
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "examples": [
        {
          "text": "The fool made many doubtful claims."
        }
      ],
      "glosses": [
        "If something is doubtful it is probably not true."
      ],
      "synonyms": [
        {
          "word": "dubious"
        }
      ]
    },
    {
      "examples": [
        {
          "text": "The teacher was doubtful of his bad students."
        }
      ],
      "glosses": [
        "If someone is doubtful they are doubting something or someone."
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈdaʊtfəl/"
    },
    {
      "audio": "en-us-doubtful.ogg",
      "tags": [
        "US"
      ]
    }
  ],
  "word": "doubtful"
}