"Twaddell hydrometer" meaning in English

{
  "etymology_text": "Inventor's surname.",
  "forms": [
    {
      "form": "Twaddell hydrometers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Twaddell hydrometer (plural Twaddell hydrometers)",
      "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"
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          "source": "w"
        },
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          "name": "English entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
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          "source": "w"
        },
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          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
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          "source": "w"
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      ],
      "glosses": [
        "A form of hydrometer for liquids heavier than water, graduated with an arbitrary scale such that the readings when multiplied by .005 and added to unity give the specific gravity."
      ],
      "id": "en-Twaddell_hydrometer-en-noun-M4dG8mC-",
      "links": [
        [
          "hydrometer",
          "hydrometer"
        ],
        [
          "liquid",
          "liquid"
        ],
        [
          "water",
          "water"
        ],
        [
          "reading",
          "reading"
        ],
        [
          "unity",
          "unity"
        ],
        [
          "specific gravity",
          "specific gravity"
        ]
      ]
    }
  ],
  "word": "Twaddell hydrometer"
}

{
  "etymology_text": "Inventor's surname.",
  "forms": [
    {
      "form": "Twaddell hydrometers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Twaddell hydrometer (plural Twaddell hydrometers)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys"
      ],
      "glosses": [
        "A form of hydrometer for liquids heavier than water, graduated with an arbitrary scale such that the readings when multiplied by .005 and added to unity give the specific gravity."
      ],
      "links": [
        [
          "hydrometer",
          "hydrometer"
        ],
        [
          "liquid",
          "liquid"
        ],
        [
          "water",
          "water"
        ],
        [
          "reading",
          "reading"
        ],
        [
          "unity",
          "unity"
        ],
        [
          "specific gravity",
          "specific gravity"
        ]
      ]
    }
  ],
  "word": "Twaddell hydrometer"
}