"second-in-command" meaning in English

{
  "forms": [
    {
      "form": "seconds-in-command",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "seconds-in-command"
      },
      "expansion": "second-in-command (plural seconds-in-command)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "glosses": [
        "Somebody ranking next below a commander."
      ],
      "id": "en-second-in-command-en-noun-MRQbJzsF",
      "links": [
        [
          "commander",
          "commander"
        ]
      ]
    },
    {
      "categories": [
        {
          "_dis": "34 66",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        }
      ],
      "examples": [
        {
          "ref": "1951 June, Dr. W. H. Chaloner, “Alexander Allan's Own Claim”, in Railway Magazine, page 416",
          "text": "Allan was first William Buddicom's and then Trevithick's second-in-command, at Edge Hill and at Crewe successively, for the period of 13½ years from February, 1840, to September, 1853, when he left Crewe to become Superintendent of the Scottish Central Railway.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Someone ranking next below the person in charge."
      ],
      "id": "en-second-in-command-en-noun-CBiIKyeQ"
    }
  ],
  "synonyms": [
    {
      "_dis1": "0 0",
      "word": "deputy"
    },
    {
      "_dis1": "0 0",
      "word": "lieutenant"
    }
  ],
  "wikipedia": [
    "second-in-command"
  ],
  "word": "second-in-command"
}

{
  "categories": [
    "English countable nouns",
    "English entries with incorrect language header",
    "English lemmas",
    "English multiword terms",
    "English nouns",
    "English nouns with irregular plurals"
  ],
  "forms": [
    {
      "form": "seconds-in-command",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "seconds-in-command"
      },
      "expansion": "second-in-command (plural seconds-in-command)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "glosses": [
        "Somebody ranking next below a commander."
      ],
      "links": [
        [
          "commander",
          "commander"
        ]
      ]
    },
    {
      "categories": [
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "1951 June, Dr. W. H. Chaloner, “Alexander Allan's Own Claim”, in Railway Magazine, page 416",
          "text": "Allan was first William Buddicom's and then Trevithick's second-in-command, at Edge Hill and at Crewe successively, for the period of 13½ years from February, 1840, to September, 1853, when he left Crewe to become Superintendent of the Scottish Central Railway.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Someone ranking next below the person in charge."
      ]
    }
  ],
  "synonyms": [
    {
      "word": "deputy"
    },
    {
      "word": "lieutenant"
    }
  ],
  "wikipedia": [
    "second-in-command"
  ],
  "word": "second-in-command"
}