"master clock" meaning in English

{
  "antonyms": [
    {
      "word": "slave clock"
    }
  ],
  "forms": [
    {
      "form": "master clocks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "master clock (plural master clocks)",
      "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": "Clocks",
          "orig": "en:Clocks",
          "parents": [
            "Machines",
            "Timekeeping",
            "Technology",
            "Time",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1960 September, M. J. Wilson, “Harlow Town station opened”, in Trains Illustrated, page 542",
          "text": "Special details of the new station are the crystal-regulated master clock in the concourse, which controls 11 \"slave\" clocks and will also control those to be installed in the Harlow Mill goods depot; [...].",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A precision clock that provides timing signals to synchronise slave clocks as part of a clock network."
      ],
      "id": "en-master_clock-en-noun-1kfuiSyp",
      "links": [
        [
          "precision",
          "precision"
        ],
        [
          "slave clock",
          "slave clock"
        ]
      ]
    }
  ],
  "word": "master clock"
}

{
  "antonyms": [
    {
      "word": "slave clock"
    }
  ],
  "forms": [
    {
      "form": "master clocks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "master clock (plural master clocks)",
      "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",
        "English terms with quotations",
        "en:Clocks"
      ],
      "examples": [
        {
          "ref": "1960 September, M. J. Wilson, “Harlow Town station opened”, in Trains Illustrated, page 542",
          "text": "Special details of the new station are the crystal-regulated master clock in the concourse, which controls 11 \"slave\" clocks and will also control those to be installed in the Harlow Mill goods depot; [...].",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A precision clock that provides timing signals to synchronise slave clocks as part of a clock network."
      ],
      "links": [
        [
          "precision",
          "precision"
        ],
        [
          "slave clock",
          "slave clock"
        ]
      ]
    }
  ],
  "word": "master clock"
}