"micromicrogram" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "micro",
        "3": "microgram"
      },
      "expansion": "micro- + microgram",
      "name": "prefix"
    }
  ],
  "etymology_text": "micro- + microgram",
  "forms": [
    {
      "form": "micromicrograms",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "micromicrogram (plural micromicrograms)",
      "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": "other",
          "name": "English terms prefixed with micro-",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "SI units",
          "orig": "en:SI units",
          "parents": [
            "Units of measure",
            "Metrology",
            "Quantity",
            "Applied sciences",
            "Mathematics",
            "Sciences",
            "Formal sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "picogram"
      ],
      "id": "en-micromicrogram-en-noun-EkXfVqh3",
      "links": [
        [
          "picogram",
          "picogram"
        ]
      ],
      "raw_glosses": [
        "(dated) picogram"
      ],
      "tags": [
        "dated"
      ]
    }
  ],
  "word": "micromicrogram"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "micro",
        "3": "microgram"
      },
      "expansion": "micro- + microgram",
      "name": "prefix"
    }
  ],
  "etymology_text": "micro- + microgram",
  "forms": [
    {
      "form": "micromicrograms",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "micromicrogram (plural micromicrograms)",
      "name": "en-noun"
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
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        "English countable nouns",
        "English dated terms",
        "English entries with incorrect language header",
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        "English nouns",
        "English terms prefixed with micro-",
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      ],
      "glosses": [
        "picogram"
      ],
      "links": [
        [
          "picogram",
          "picogram"
        ]
      ],
      "raw_glosses": [
        "(dated) picogram"
      ],
      "tags": [
        "dated"
      ]
    }
  ],
  "word": "micromicrogram"
}