"flint glass" meaning in English

{
  "etymology_text": "Originally made of calcined flints.",
  "forms": [
    {
      "form": "flint glasses",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "flint glass (countable and uncountable, plural flint glasses)",
      "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": "topical",
          "langcode": "en",
          "name": "Glass",
          "orig": "en:Glass",
          "parents": [
            "Materials",
            "Manufacturing",
            "Human activity",
            "Human behaviour",
            "Human",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A soft, heavy, brilliant glass, consisting essentially of a silicate of lead and potassium. It is used for tableware and in optical instruments."
      ],
      "id": "en-flint_glass-en-noun-fsBkUrJq",
      "links": [
        [
          "glass",
          "glass"
        ],
        [
          "silicate",
          "silicate"
        ],
        [
          "lead",
          "lead"
        ],
        [
          "potassium",
          "potassium"
        ],
        [
          "tableware",
          "tableware"
        ],
        [
          "optical",
          "optical"
        ],
        [
          "instrument",
          "instrument"
        ]
      ],
      "synonyms": [
        {
          "word": "crystal glass"
        }
      ],
      "tags": [
        "countable",
        "uncountable"
      ]
    }
  ],
  "word": "flint glass"
}

{
  "etymology_text": "Originally made of calcined flints.",
  "forms": [
    {
      "form": "flint glasses",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "~"
      },
      "expansion": "flint glass (countable and uncountable, plural flint glasses)",
      "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 uncountable nouns",
        "en:Glass"
      ],
      "glosses": [
        "A soft, heavy, brilliant glass, consisting essentially of a silicate of lead and potassium. It is used for tableware and in optical instruments."
      ],
      "links": [
        [
          "glass",
          "glass"
        ],
        [
          "silicate",
          "silicate"
        ],
        [
          "lead",
          "lead"
        ],
        [
          "potassium",
          "potassium"
        ],
        [
          "tableware",
          "tableware"
        ],
        [
          "optical",
          "optical"
        ],
        [
          "instrument",
          "instrument"
        ]
      ],
      "tags": [
        "countable",
        "uncountable"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "crystal glass"
    }
  ],
  "word": "flint glass"
}