"Sunday girl" meaning in English

{
  "forms": [
    {
      "form": "Sunday girls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Sunday girl (plural Sunday girls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "Are you taking your Sunday girl to the dance?",
          "type": "example"
        },
        {
          "ref": "1884, Edwin A. Frear, From Pier 39",
          "text": "Just as one is rounded, too late to entirely avoid it, is seen exactly at the turn a single chaise containing a youth and his Sunday girl.",
          "type": "quotation"
        },
        {
          "ref": "1960, Arizona and the West",
          "text": "In twenty-four hours the pot had filled to three dollars, and Charlie, who was going to town to see his Sunday girl, was delegated to subscribe to “some good newspaper.”",
          "type": "quotation"
        }
      ],
      "glosses": [
        "girlfriend"
      ],
      "id": "en-Sunday_girl-en-noun-6pKmEnvz",
      "links": [
        [
          "girlfriend",
          "girlfriend"
        ]
      ],
      "raw_glosses": [
        "(US, obsolete, slang) girlfriend"
      ],
      "tags": [
        "US",
        "obsolete",
        "slang"
      ]
    }
  ],
  "word": "Sunday girl"
}

{
  "forms": [
    {
      "form": "Sunday girls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Sunday girl (plural Sunday girls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "American English",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English slang",
        "English terms with obsolete senses",
        "English terms with quotations",
        "English terms with usage examples"
      ],
      "examples": [
        {
          "text": "Are you taking your Sunday girl to the dance?",
          "type": "example"
        },
        {
          "ref": "1884, Edwin A. Frear, From Pier 39",
          "text": "Just as one is rounded, too late to entirely avoid it, is seen exactly at the turn a single chaise containing a youth and his Sunday girl.",
          "type": "quotation"
        },
        {
          "ref": "1960, Arizona and the West",
          "text": "In twenty-four hours the pot had filled to three dollars, and Charlie, who was going to town to see his Sunday girl, was delegated to subscribe to “some good newspaper.”",
          "type": "quotation"
        }
      ],
      "glosses": [
        "girlfriend"
      ],
      "links": [
        [
          "girlfriend",
          "girlfriend"
        ]
      ],
      "raw_glosses": [
        "(US, obsolete, slang) girlfriend"
      ],
      "tags": [
        "US",
        "obsolete",
        "slang"
      ]
    }
  ],
  "word": "Sunday girl"
}