"bác cổ" meaning in Vietnamien

{
  "categories": [
    {
      "kind": "other",
      "name": "Adjectifs en vietnamien",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Vietnamien",
      "orig": "vietnamien",
      "parents": [],
      "source": "w"
    }
  ],
  "lang": "Vietnamien",
  "lang_code": "vi",
  "pos": "adj",
  "pos_title": "Adjectif",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Termes désuets en vietnamien",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Érudit en matière d’histoire ancienne."
      ],
      "id": "fr-bác_cổ-vi-adj-y80qT4P2",
      "tags": [
        "obsolete"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "\\bak˦˥.ko˧˨˧\\"
    }
  ],
  "word": "bác cổ"
}

{
  "categories": [
    "Adjectifs en vietnamien",
    "vietnamien"
  ],
  "lang": "Vietnamien",
  "lang_code": "vi",
  "pos": "adj",
  "pos_title": "Adjectif",
  "senses": [
    {
      "categories": [
        "Termes désuets en vietnamien"
      ],
      "glosses": [
        "Érudit en matière d’histoire ancienne."
      ],
      "tags": [
        "obsolete"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "\\bak˦˥.ko˧˨˧\\"
    }
  ],
  "word": "bác cổ"
}