"hydraulic retention time" meaning in English

{
  "forms": [
    {
      "form": "hydraulic retention times",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "hydraulic retention time (plural hydraulic retention times)",
      "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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          "parents": [
            "Entries with topic 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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Hydrology",
          "orig": "en:Hydrology",
          "parents": [
            "Earth sciences",
            "Water",
            "Sciences",
            "Liquids",
            "All topics",
            "Matter",
            "Fundamental",
            "Chemistry",
            "Nature"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "a measure of the average length of time that a soluble compound remains in a constructed reactor"
      ],
      "id": "en-hydraulic_retention_time-en-noun-qEP4dWDr",
      "translations": [
        {
          "code": "ro",
          "lang": "Romanian",
          "sense": "a measure of the average length of time that a soluble compound remains in a constructed reactor",
          "word": "timp de retenție hidraulică"
        }
      ],
      "wikipedia": [
        "hydraulic retention time"
      ]
    }
  ],
  "word": "hydraulic retention time"
}

{
  "forms": [
    {
      "form": "hydraulic retention times",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "hydraulic retention time (plural hydraulic retention times)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with topic categories using raw markup",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys",
        "en:Hydrology"
      ],
      "glosses": [
        "a measure of the average length of time that a soluble compound remains in a constructed reactor"
      ],
      "wikipedia": [
        "hydraulic retention time"
      ]
    }
  ],
  "translations": [
    {
      "code": "ro",
      "lang": "Romanian",
      "sense": "a measure of the average length of time that a soluble compound remains in a constructed reactor",
      "word": "timp de retenție hidraulică"
    }
  ],
  "word": "hydraulic retention time"
}