"Harvard comma" meaning in English

{
  "etymology_text": "From Harvard University Press, where such use is the house style.",
  "forms": [
    {
      "form": "Harvard commas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Harvard comma (plural Harvard commas)",
      "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": "Punctuation marks",
          "orig": "en:Punctuation marks",
          "parents": [
            "Letters, symbols, and punctuation",
            "Symbols",
            "Orthography",
            "Writing",
            "Human behaviour",
            "Language",
            "Human",
            "Communication",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Typography",
          "orig": "en:Typography",
          "parents": [
            "Printing",
            "Writing",
            "Industries",
            "Human behaviour",
            "Language",
            "Business",
            "Human",
            "Communication",
            "Economics",
            "Society",
            "All topics",
            "Social sciences",
            "Fundamental",
            "Sciences"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The serial comma."
      ],
      "id": "en-Harvard_comma-en-noun-eFDsojTQ",
      "links": [
        [
          "typography",
          "typography"
        ],
        [
          "serial comma",
          "serial comma"
        ]
      ],
      "raw_glosses": [
        "(typography, US) The serial comma."
      ],
      "synonyms": [
        {
          "english": "UK & US",
          "word": "Oxford comma"
        },
        {
          "english": "UK & US",
          "word": "serial comma"
        }
      ],
      "tags": [
        "US"
      ],
      "topics": [
        "media",
        "publishing",
        "typography"
      ],
      "wikipedia": [
        "Harvard University Press"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-us-Harvard comma.oga",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/2/20/En-us-Harvard_comma.oga/En-us-Harvard_comma.oga.mp3",
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  "word": "Harvard comma"
}

{
  "etymology_text": "From Harvard University Press, where such use is the house style.",
  "forms": [
    {
      "form": "Harvard commas",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Harvard comma (plural Harvard commas)",
      "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",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Punctuation marks",
        "en:Typography"
      ],
      "glosses": [
        "The serial comma."
      ],
      "links": [
        [
          "typography",
          "typography"
        ],
        [
          "serial comma",
          "serial comma"
        ]
      ],
      "raw_glosses": [
        "(typography, US) The serial comma."
      ],
      "synonyms": [
        {
          "english": "UK & US",
          "word": "Oxford comma"
        },
        {
          "english": "UK & US",
          "word": "serial comma"
        }
      ],
      "tags": [
        "US"
      ],
      "topics": [
        "media",
        "publishing",
        "typography"
      ],
      "wikipedia": [
        "Harvard University Press"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-us-Harvard comma.oga",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/2/20/En-us-Harvard_comma.oga/En-us-Harvard_comma.oga.mp3",
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  ],
  "word": "Harvard comma"
}