"dear Sir" meaning in English

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "phrase"
      },
      "expansion": "dear Sir",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Used as the salutation at the beginning of a formal letter when addressing persons – assumed to be male – of unknown names."
      ],
      "id": "en-dear_Sir-en-phrase-plalIigE",
      "links": [
        [
          "salutation",
          "salutation#English"
        ]
      ],
      "raw_glosses": [
        "(dated) Used as the salutation at the beginning of a formal letter when addressing persons – assumed to be male – of unknown names."
      ],
      "synonyms": [
        {
          "word": "dear sir"
        },
        {
          "word": "dear Sir or Madam"
        },
        {
          "english": "if gender of addressee is unknown",
          "word": "dear Sir/Madam"
        },
        {
          "word": "dear Sirs"
        },
        {
          "english": "with multiple addressees",
          "word": "dear sirs"
        }
      ],
      "tags": [
        "dated"
      ],
      "translations": [
        {
          "code": "es",
          "lang": "Spanish",
          "sense": "Translations",
          "word": "muy señor mío"
        },
        {
          "code": "es",
          "lang": "Spanish",
          "sense": "Translations",
          "word": "muy señor nuestro"
        }
      ]
    }
  ],
  "word": "dear Sir"
}

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "phrase"
      },
      "expansion": "dear Sir",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "senses": [
    {
      "categories": [
        "English dated terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English phrases",
        "Translation table header lacks gloss"
      ],
      "glosses": [
        "Used as the salutation at the beginning of a formal letter when addressing persons – assumed to be male – of unknown names."
      ],
      "links": [
        [
          "salutation",
          "salutation#English"
        ]
      ],
      "raw_glosses": [
        "(dated) Used as the salutation at the beginning of a formal letter when addressing persons – assumed to be male – of unknown names."
      ],
      "tags": [
        "dated"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "dear sir"
    },
    {
      "word": "dear Sir or Madam"
    },
    {
      "english": "if gender of addressee is unknown",
      "word": "dear Sir/Madam"
    },
    {
      "word": "dear Sirs"
    },
    {
      "english": "with multiple addressees",
      "word": "dear sirs"
    }
  ],
  "translations": [
    {
      "code": "es",
      "lang": "Spanish",
      "sense": "Translations",
      "word": "muy señor mío"
    },
    {
      "code": "es",
      "lang": "Spanish",
      "sense": "Translations",
      "word": "muy señor nuestro"
    }
  ],
  "word": "dear Sir"
}