"button man" meaning in English

{
  "forms": [
    {
      "form": "button men",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "button men"
      },
      "expansion": "button man (plural button men)",
      "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"
        }
      ],
      "examples": [
        {
          "ref": "2000, James Carville, Stickin': The Case for Loyalty, page 13",
          "text": "I was called a \"buffoon\" in the paper of record, the New York Times, and the Washington Post described me fondly as \"Clinton's gunsel,\" his button man",
          "type": "quotation"
        },
        {
          "ref": "2000, Stuart Woods, Worst Fears Realized, page 177",
          "text": "\"Twenty years ago, he was Little Pete Drago, a button man for the boys on Mulberry Street. He's probably got twenty notches on his piece",
          "type": "quotation"
        },
        {
          "ref": "2005, Jeffery Deaver, Garden of Beasts: A Novel of Berlin 1936, page 44",
          "text": "But death is never symmetrical and tidy, and the button man had nothing to say.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A contract killer; a professional assassin."
      ],
      "id": "en-button_man-en-noun-FODq41l5",
      "links": [
        [
          "contract killer",
          "contract killer"
        ]
      ],
      "raw_glosses": [
        "(slang) A contract killer; a professional assassin."
      ],
      "tags": [
        "slang"
      ]
    }
  ],
  "word": "button man"
}

{
  "forms": [
    {
      "form": "button men",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "button men"
      },
      "expansion": "button man (plural button men)",
      "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 slang",
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "2000, James Carville, Stickin': The Case for Loyalty, page 13",
          "text": "I was called a \"buffoon\" in the paper of record, the New York Times, and the Washington Post described me fondly as \"Clinton's gunsel,\" his button man",
          "type": "quotation"
        },
        {
          "ref": "2000, Stuart Woods, Worst Fears Realized, page 177",
          "text": "\"Twenty years ago, he was Little Pete Drago, a button man for the boys on Mulberry Street. He's probably got twenty notches on his piece",
          "type": "quotation"
        },
        {
          "ref": "2005, Jeffery Deaver, Garden of Beasts: A Novel of Berlin 1936, page 44",
          "text": "But death is never symmetrical and tidy, and the button man had nothing to say.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A contract killer; a professional assassin."
      ],
      "links": [
        [
          "contract killer",
          "contract killer"
        ]
      ],
      "raw_glosses": [
        "(slang) A contract killer; a professional assassin."
      ],
      "tags": [
        "slang"
      ]
    }
  ],
  "word": "button man"
}