"hydro complex" meaning in English

{
  "forms": [
    {
      "form": "hydro complexes",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "hydro complex (plural hydro complexes)",
      "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": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Hydrogen",
          "orig": "en:Hydrogen",
          "parents": [
            "Chemical elements",
            "Matter",
            "Chemistry",
            "Nature",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "a hydrido complex"
      ],
      "id": "en-hydro_complex-en-noun-z1yvGDfn",
      "links": [
        [
          "hydrido complex",
          "hydrido complex"
        ]
      ]
    }
  ],
  "word": "hydro complex"
}

{
  "forms": [
    {
      "form": "hydro complexes",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "hydro complex (plural hydro complexes)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "en:Hydrogen"
      ],
      "glosses": [
        "a hydrido complex"
      ],
      "links": [
        [
          "hydrido complex",
          "hydrido complex"
        ]
      ]
    }
  ],
  "word": "hydro complex"
}