"millimicrosecond" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "millimicro-",
        "3": "second"
      },
      "expansion": "millimicro- + second",
      "name": "prefix"
    },
    {
      "args": {
        "1": "en",
        "2": "milli<id:thousandth>",
        "3": "microsecond"
      },
      "expansion": "milli- + microsecond",
      "name": "prefix"
    }
  ],
  "etymology_text": "From millimicro- + second / milli- + microsecond.",
  "forms": [
    {
      "form": "millimicroseconds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "millimicrosecond (plural millimicroseconds)",
      "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 milli- (thousandth)",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms prefixed with millimicro-",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "One thousandth of a microsecond"
      ],
      "id": "en-millimicrosecond-en-noun-dPpwUl7p",
      "links": [
        [
          "microsecond",
          "microsecond"
        ]
      ]
    }
  ],
  "word": "millimicrosecond"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "millimicro-",
        "3": "second"
      },
      "expansion": "millimicro- + second",
      "name": "prefix"
    },
    {
      "args": {
        "1": "en",
        "2": "milli<id:thousandth>",
        "3": "microsecond"
      },
      "expansion": "milli- + microsecond",
      "name": "prefix"
    }
  ],
  "etymology_text": "From millimicro- + second / milli- + microsecond.",
  "forms": [
    {
      "form": "millimicroseconds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "millimicrosecond (plural millimicroseconds)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English nouns",
        "English terms prefixed with milli- (thousandth)",
        "English terms prefixed with millimicro-",
        "Pages with 1 entry"
      ],
      "glosses": [
        "One thousandth of a microsecond"
      ],
      "links": [
        [
          "microsecond",
          "microsecond"
        ]
      ]
    }
  ],
  "word": "millimicrosecond"
}