"trunk monkey" meaning in English

{
  "etymology_links": [
    [
      "trunk",
      "trunk#English"
    ],
    [
      "monkey",
      "monkey#English"
    ],
    [
      "trunk",
      "trunk#English"
    ]
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "trunk",
        "3": "monkey"
      },
      "expansion": "trunk + monkey",
      "name": "compound"
    }
  ],
  "etymology_text": "trunk + monkey. From being in the rear, back seat, the notional trunk (“boot”).",
  "forms": [
    {
      "form": "trunk monkeys",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "trunk monkey (plural trunk monkeys)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Aviation",
          "orig": "en:Aviation",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Military",
          "orig": "en:Military",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Rear-seat non-piloting aviator in a two-seat combat aircraft; the WSO, RIO, etc."
      ],
      "hypernyms": [
        {
          "word": "backseater"
        },
        {
          "word": "rearseater"
        }
      ],
      "id": "en-trunk_monkey-en-noun-HeBn9pKY",
      "links": [
        [
          "military",
          "military"
        ],
        [
          "aviation",
          "aviation"
        ],
        [
          "WSO",
          "WSO#English"
        ],
        [
          "RIO",
          "RIO#English"
        ]
      ],
      "raw_glosses": [
        "(military, aviation, slang, humorous) Rear-seat non-piloting aviator in a two-seat combat aircraft; the WSO, RIO, etc."
      ],
      "tags": [
        "humorous",
        "slang"
      ],
      "topics": [
        "aeronautics",
        "aerospace",
        "aviation",
        "business",
        "engineering",
        "government",
        "military",
        "natural-sciences",
        "physical-sciences",
        "politics",
        "war"
      ]
    }
  ],
  "word": "trunk monkey"
}

{
  "etymology_links": [
    [
      "trunk",
      "trunk#English"
    ],
    [
      "monkey",
      "monkey#English"
    ],
    [
      "trunk",
      "trunk#English"
    ]
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "trunk",
        "3": "monkey"
      },
      "expansion": "trunk + monkey",
      "name": "compound"
    }
  ],
  "etymology_text": "trunk + monkey. From being in the rear, back seat, the notional trunk (“boot”).",
  "forms": [
    {
      "form": "trunk monkeys",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "trunk monkey (plural trunk monkeys)",
      "name": "en-noun"
    }
  ],
  "hypernyms": [
    {
      "word": "backseater"
    },
    {
      "word": "rearseater"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English compound terms",
        "English countable nouns",
        "English entries with incorrect language header",
        "English humorous terms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English slang",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Aviation",
        "en:Military"
      ],
      "glosses": [
        "Rear-seat non-piloting aviator in a two-seat combat aircraft; the WSO, RIO, etc."
      ],
      "links": [
        [
          "military",
          "military"
        ],
        [
          "aviation",
          "aviation"
        ],
        [
          "WSO",
          "WSO#English"
        ],
        [
          "RIO",
          "RIO#English"
        ]
      ],
      "raw_glosses": [
        "(military, aviation, slang, humorous) Rear-seat non-piloting aviator in a two-seat combat aircraft; the WSO, RIO, etc."
      ],
      "tags": [
        "humorous",
        "slang"
      ],
      "topics": [
        "aeronautics",
        "aerospace",
        "aviation",
        "business",
        "engineering",
        "government",
        "military",
        "natural-sciences",
        "physical-sciences",
        "politics",
        "war"
      ]
    }
  ],
  "word": "trunk monkey"
}