"Mad King George" meaning in English

{
  "etymology_text": "In reference to the numerous episodes of acute mania suffered from in later life; typically thought to be due to porphyria or bipolar disorder.",
  "head_templates": [
    {
      "args": {
        "head": "Mad King George"
      },
      "expansion": "Mad King George",
      "name": "en-prop"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Nicknames of individuals",
          "orig": "en:Nicknames of individuals",
          "parents": [
            "Individuals",
            "Nicknames",
            "People",
            "Names",
            "Human",
            "All topics",
            "Proper nouns",
            "Terms by semantic function",
            "Fundamental",
            "Nouns",
            "Lemmas"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A nickname for King George III of the United Kingdom."
      ],
      "id": "en-Mad_King_George-en-name-seF~Q1Ta",
      "links": [
        [
          "nickname",
          "nickname#English"
        ],
        [
          "King George III",
          "w:King George III"
        ],
        [
          "United Kingdom",
          "United Kingdom#English"
        ]
      ],
      "raw_glosses": [
        "(historical, dated) A nickname for King George III of the United Kingdom."
      ],
      "synonyms": [
        {
          "word": "Farmer George"
        }
      ],
      "tags": [
        "dated",
        "historical"
      ]
    }
  ],
  "word": "Mad King George"
}

{
  "etymology_text": "In reference to the numerous episodes of acute mania suffered from in later life; typically thought to be due to porphyria or bipolar disorder.",
  "head_templates": [
    {
      "args": {
        "head": "Mad King George"
      },
      "expansion": "Mad King George",
      "name": "en-prop"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
      "categories": [
        "English dated terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English proper nouns",
        "English terms with historical senses",
        "English uncountable nouns",
        "en:Nicknames of individuals"
      ],
      "glosses": [
        "A nickname for King George III of the United Kingdom."
      ],
      "links": [
        [
          "nickname",
          "nickname#English"
        ],
        [
          "King George III",
          "w:King George III"
        ],
        [
          "United Kingdom",
          "United Kingdom#English"
        ]
      ],
      "raw_glosses": [
        "(historical, dated) A nickname for King George III of the United Kingdom."
      ],
      "synonyms": [
        {
          "word": "Farmer George"
        }
      ],
      "tags": [
        "dated",
        "historical"
      ]
    }
  ],
  "word": "Mad King George"
}