"main rag" meaning in English

{
  "forms": [
    {
      "form": "main rags",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "main rag (plural main rags)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Theater",
          "orig": "en:Theater",
          "parents": [
            "Art",
            "Entertainment",
            "Culture",
            "Society",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Synonym of front curtain"
      ],
      "id": "en-main_rag-en-noun-tn~FRPda",
      "links": [
        [
          "theater",
          "theater"
        ],
        [
          "front curtain",
          "front curtain#English"
        ]
      ],
      "raw_glosses": [
        "(theater, slang) Synonym of front curtain"
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "front curtain"
        }
      ],
      "tags": [
        "slang"
      ],
      "topics": [
        "entertainment",
        "lifestyle",
        "theater"
      ]
    }
  ],
  "word": "main rag"
}

{
  "forms": [
    {
      "form": "main rags",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "main rag (plural main rags)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English slang",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Theater"
      ],
      "glosses": [
        "Synonym of front curtain"
      ],
      "links": [
        [
          "theater",
          "theater"
        ],
        [
          "front curtain",
          "front curtain#English"
        ]
      ],
      "raw_glosses": [
        "(theater, slang) Synonym of front curtain"
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "front curtain"
        }
      ],
      "tags": [
        "slang"
      ],
      "topics": [
        "entertainment",
        "lifestyle",
        "theater"
      ]
    }
  ],
  "word": "main rag"
}