"tapa dura" meaning in Spanish

{
  "forms": [
    {
      "form": "tapas duras",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "tapa dura f (plural tapas duras)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
    {
      "antonyms": [
        {
          "word": "libro de bolsillo"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "Spanish entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "es",
          "name": "Books",
          "orig": "es:Books",
          "parents": [
            "Literature",
            "Mass media",
            "Culture",
            "Entertainment",
            "Writing",
            "Media",
            "Society",
            "Human behaviour",
            "Language",
            "Communication",
            "All topics",
            "Human",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "hardback, hardcover"
      ],
      "id": "en-tapa_dura-es-noun-uTfB2QLE",
      "links": [
        [
          "hardback",
          "hardback"
        ],
        [
          "hardcover",
          "hardcover"
        ]
      ],
      "tags": [
        "feminine"
      ]
    }
  ],
  "word": "tapa dura"
}

{
  "forms": [
    {
      "form": "tapas duras",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "tapa dura f (plural tapas duras)",
      "name": "es-noun"
    }
  ],
  "lang": "Spanish",
  "lang_code": "es",
  "pos": "noun",
  "senses": [
    {
      "antonyms": [
        {
          "word": "libro de bolsillo"
        }
      ],
      "categories": [
        "Spanish countable nouns",
        "Spanish entries with incorrect language header",
        "Spanish feminine nouns",
        "Spanish lemmas",
        "Spanish multiword terms",
        "Spanish nouns",
        "es:Books"
      ],
      "glosses": [
        "hardback, hardcover"
      ],
      "links": [
        [
          "hardback",
          "hardback"
        ],
        [
          "hardcover",
          "hardcover"
        ]
      ],
      "tags": [
        "feminine"
      ]
    }
  ],
  "word": "tapa dura"
}