"head girl" meaning in English

{
  "forms": [
    {
      "form": "head girls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "head girl (plural head girls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "British English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A girl chosen to lead a school's sixth form, whose duties may include representing the school and organising the prefects."
      ],
      "id": "en-head_girl-en-noun-2SqDlFKF",
      "links": [
        [
          "school",
          "school"
        ],
        [
          "sixth form",
          "sixth form"
        ],
        [
          "prefect",
          "prefect"
        ]
      ],
      "raw_glosses": [
        "(British) A girl chosen to lead a school's sixth form, whose duties may include representing the school and organising the prefects."
      ],
      "related": [
        {
          "word": "head boy"
        }
      ],
      "tags": [
        "British"
      ],
      "wikipedia": [
        "head girl"
      ]
    }
  ],
  "word": "head girl"
}

{
  "forms": [
    {
      "form": "head girls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "head girl (plural head girls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "head boy"
    }
  ],
  "senses": [
    {
      "categories": [
        "British English",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A girl chosen to lead a school's sixth form, whose duties may include representing the school and organising the prefects."
      ],
      "links": [
        [
          "school",
          "school"
        ],
        [
          "sixth form",
          "sixth form"
        ],
        [
          "prefect",
          "prefect"
        ]
      ],
      "raw_glosses": [
        "(British) A girl chosen to lead a school's sixth form, whose duties may include representing the school and organising the prefects."
      ],
      "tags": [
        "British"
      ],
      "wikipedia": [
        "head girl"
      ]
    }
  ],
  "word": "head girl"
}