"flatter oneself" meaning in English

{
  "forms": [
    {
      "form": "flatters oneself",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "flattering oneself",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "flattered oneself",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "flattered oneself",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "flatter oneself (third-person singular simple present flatters oneself, present participle flattering oneself, simple past and past participle flattered oneself)",
      "name": "en-verb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "He flatters himself that he has a good voice."
        }
      ],
      "glosses": [
        "To have the false but pleasant belief that something is true."
      ],
      "id": "en-flatter_oneself-en-verb-FwOsXTpP",
      "raw_glosses": [
        "(reflexive) To have the false but pleasant belief that something is true."
      ],
      "tags": [
        "reflexive"
      ]
    }
  ],
  "word": "flatter oneself"
}

{
  "forms": [
    {
      "form": "flatters oneself",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "flattering oneself",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "flattered oneself",
      "tags": [
        "participle",
        "past"
      ]
    },
    {
      "form": "flattered oneself",
      "tags": [
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "*"
      },
      "expansion": "flatter oneself (third-person singular simple present flatters oneself, present participle flattering oneself, simple past and past participle flattered oneself)",
      "name": "en-verb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English reflexive verbs",
        "English verbs"
      ],
      "examples": [
        {
          "text": "He flatters himself that he has a good voice."
        }
      ],
      "glosses": [
        "To have the false but pleasant belief that something is true."
      ],
      "raw_glosses": [
        "(reflexive) To have the false but pleasant belief that something is true."
      ],
      "tags": [
        "reflexive"
      ]
    }
  ],
  "word": "flatter oneself"
}