"mercury switch" meaning in English

{
  "forms": [
    {
      "form": "mercury switches",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "mercury switch (plural mercury switches)",
      "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": "topical",
          "langcode": "en",
          "name": "Electricity",
          "orig": "en:Electricity",
          "parents": [
            "Electromagnetism",
            "Physics",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Mercury (element)",
          "orig": "en:Mercury (element)",
          "parents": [
            "Transition metals",
            "Chemical elements",
            "Metals",
            "Matter",
            "Metallurgy",
            "Chemistry",
            "Nature",
            "Technology",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A switch that opens and closes an electric circuit through a small amount of liquid mercury."
      ],
      "id": "en-mercury_switch-en-noun-7fNdOV6Y",
      "links": [
        [
          "switch",
          "switch"
        ],
        [
          "electric circuit",
          "electric circuit"
        ],
        [
          "liquid",
          "liquid"
        ],
        [
          "mercury",
          "mercury"
        ]
      ],
      "wikipedia": [
        "mercury switch"
      ]
    }
  ],
  "sounds": [
    {
      "rhymes": "-ɪtʃ"
    }
  ],
  "word": "mercury switch"
}

{
  "forms": [
    {
      "form": "mercury switches",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "mercury switch (plural mercury switches)",
      "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",
        "Rhymes:English/ɪtʃ",
        "Rhymes:English/ɪtʃ/4 syllables",
        "en:Electricity",
        "en:Mercury (element)"
      ],
      "glosses": [
        "A switch that opens and closes an electric circuit through a small amount of liquid mercury."
      ],
      "links": [
        [
          "switch",
          "switch"
        ],
        [
          "electric circuit",
          "electric circuit"
        ],
        [
          "liquid",
          "liquid"
        ],
        [
          "mercury",
          "mercury"
        ]
      ],
      "wikipedia": [
        "mercury switch"
      ]
    }
  ],
  "sounds": [
    {
      "rhymes": "-ɪtʃ"
    }
  ],
  "word": "mercury switch"
}