"Doomsday Clock" meaning in English

{
  "forms": [
    {
      "form": "the Doomsday Clock",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "def": "1",
        "head": "Doomsday Clock"
      },
      "expansion": "the Doomsday Clock",
      "name": "en-prop"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "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": "Nuclear warfare",
          "orig": "en:Nuclear warfare",
          "parents": [
            "War",
            "Weapons",
            "Conflict",
            "Military",
            "Violence",
            "Hunting",
            "Tools",
            "Human behaviour",
            "Society",
            "Human activity",
            "Technology",
            "Human",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A symbol in the form of a clock, representing the likelihood of a human-made global catastrophe, in the opinion of the members of the Bulletin of the Atomic Scientists. Its hands are moved backward or forward in response to world events, with midnight representing the onset of catastrophe."
      ],
      "id": "en-Doomsday_Clock-en-name-7yFG6-ik"
    }
  ],
  "word": "Doomsday Clock"
}

{
  "forms": [
    {
      "form": "the Doomsday Clock",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "def": "1",
        "head": "Doomsday Clock"
      },
      "expansion": "the Doomsday Clock",
      "name": "en-prop"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "name",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English proper nouns",
        "English uncountable nouns",
        "en:Nuclear warfare"
      ],
      "glosses": [
        "A symbol in the form of a clock, representing the likelihood of a human-made global catastrophe, in the opinion of the members of the Bulletin of the Atomic Scientists. Its hands are moved backward or forward in response to world events, with midnight representing the onset of catastrophe."
      ]
    }
  ],
  "word": "Doomsday Clock"
}