"K-9 unit" meaning in English

{
  "etymology_text": "Humorous homophone of canine from an old vaudeville show.",
  "forms": [
    {
      "form": "K-9 units",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "head": "K-9 unit"
      },
      "expansion": "K-9 unit (plural K-9 units)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American 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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Law enforcement",
          "orig": "en:Law enforcement",
          "parents": [
            "Crime prevention",
            "Emergency services",
            "Law",
            "Crime",
            "Public safety",
            "Justice",
            "Criminal law",
            "Society",
            "Public administration",
            "Security",
            "All topics",
            "Government",
            "Fundamental",
            "Politics"
          ],
          "source": "w"
        },
        {
          "kind": "lifeform",
          "langcode": "en",
          "name": "Working dogs",
          "orig": "en:Working dogs",
          "parents": [
            "Dogs",
            "Canids",
            "Carnivores",
            "Mammals",
            "Vertebrates",
            "Chordates",
            "Animals",
            "Lifeforms",
            "All topics",
            "Life",
            "Fundamental",
            "Nature"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A police dog or a police dog and its handler."
      ],
      "id": "en-K-9_unit-en-noun-JeaoZi-2",
      "links": [
        [
          "police dog",
          "police dog"
        ],
        [
          "handler",
          "handler"
        ]
      ],
      "raw_glosses": [
        "(US) A police dog or a police dog and its handler."
      ],
      "tags": [
        "US"
      ]
    }
  ],
  "word": "K-9 unit"
}

{
  "etymology_text": "Humorous homophone of canine from an old vaudeville show.",
  "forms": [
    {
      "form": "K-9 units",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "head": "K-9 unit"
      },
      "expansion": "K-9 unit (plural K-9 units)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "American English",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms spelled with numbers",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Law enforcement",
        "en:Working dogs"
      ],
      "glosses": [
        "A police dog or a police dog and its handler."
      ],
      "links": [
        [
          "police dog",
          "police dog"
        ],
        [
          "handler",
          "handler"
        ]
      ],
      "raw_glosses": [
        "(US) A police dog or a police dog and its handler."
      ],
      "tags": [
        "US"
      ]
    }
  ],
  "word": "K-9 unit"
}