"groundmass" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "ground",
        "3": "mass"
      },
      "expansion": "ground + mass",
      "name": "compound"
    }
  ],
  "etymology_text": "ground + mass",
  "forms": [
    {
      "form": "groundmasses",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "groundmass (plural groundmasses)",
      "name": "en-noun"
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  ],
  "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": "Geology",
          "orig": "en:Geology",
          "parents": [
            "Earth sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The matrix of fine-grained crystalline material in which larger crystals are embedded."
      ],
      "id": "en-groundmass-en-noun-0jyp498B",
      "links": [
        [
          "geology",
          "geology"
        ]
      ],
      "raw_glosses": [
        "(geology) The matrix of fine-grained crystalline material in which larger crystals are embedded."
      ],
      "topics": [
        "geography",
        "geology",
        "natural-sciences"
      ]
    }
  ],
  "word": "groundmass"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "ground",
        "3": "mass"
      },
      "expansion": "ground + mass",
      "name": "compound"
    }
  ],
  "etymology_text": "ground + mass",
  "forms": [
    {
      "form": "groundmasses",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "groundmass (plural groundmasses)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English compound terms",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English nouns",
        "en:Geology"
      ],
      "glosses": [
        "The matrix of fine-grained crystalline material in which larger crystals are embedded."
      ],
      "links": [
        [
          "geology",
          "geology"
        ]
      ],
      "raw_glosses": [
        "(geology) The matrix of fine-grained crystalline material in which larger crystals are embedded."
      ],
      "topics": [
        "geography",
        "geology",
        "natural-sciences"
      ]
    }
  ],
  "word": "groundmass"
}