"silver alert" meaning in English

{
  "etymology_text": "Introduced in 2005 by Oklahoma state representative Fred Perry, modelled on amber alert. Silver suggests the grey hair of elderly people; compare silver fox.",
  "forms": [
    {
      "form": "silver alerts",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "silver alert (plural silver alerts)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Canadian English",
          "parents": [],
          "source": "w"
        },
        {
          "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": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A public notification of a missing person, especially a senior with dementia."
      ],
      "id": "en-silver_alert-en-noun-yHZb~Sc1",
      "links": [
        [
          "senior",
          "senior"
        ],
        [
          "dementia",
          "dementia"
        ]
      ],
      "raw_glosses": [
        "(US, Canada) A public notification of a missing person, especially a senior with dementia."
      ],
      "tags": [
        "Canada",
        "US"
      ],
      "wikipedia": [
        "silver alert"
      ]
    }
  ],
  "word": "silver alert"
}

{
  "etymology_text": "Introduced in 2005 by Oklahoma state representative Fred Perry, modelled on amber alert. Silver suggests the grey hair of elderly people; compare silver fox.",
  "forms": [
    {
      "form": "silver alerts",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "silver alert (plural silver alerts)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "American English",
        "Canadian English",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A public notification of a missing person, especially a senior with dementia."
      ],
      "links": [
        [
          "senior",
          "senior"
        ],
        [
          "dementia",
          "dementia"
        ]
      ],
      "raw_glosses": [
        "(US, Canada) A public notification of a missing person, especially a senior with dementia."
      ],
      "tags": [
        "Canada",
        "US"
      ],
      "wikipedia": [
        "silver alert"
      ]
    }
  ],
  "word": "silver alert"
}