"Petrov Defence" meaning in English

{
  "etymology_text": "Popularized by Russian chess master Alexander Petrov.",
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        "head": "Petrov Defence"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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        {
          "kind": "topical",
          "langcode": "en",
          "name": "Chess openings",
          "orig": "en:Chess openings",
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      "glosses": [
        "A chess opening beginning 1. e4 e5 2. Nf3 Nf6."
      ],
      "id": "en-Petrov_Defence-en-noun-9V1PBw2l",
      "links": [
        [
          "chess",
          "chess"
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        [
          "opening",
          "opening"
        ]
      ],
      "synonyms": [
        {
          "word": "Russian Game"
        },
        {
          "word": "Petrov's Defence"
        },
        {
          "word": "Petrov's Defense"
        },
        {
          "word": "Petrov Defense"
        }
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    }
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  "word": "Petrov Defence"
}

{
  "etymology_text": "Popularized by Russian chess master Alexander Petrov.",
  "head_templates": [
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        "head": "Petrov Defence"
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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        "en:Chess openings"
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      "glosses": [
        "A chess opening beginning 1. e4 e5 2. Nf3 Nf6."
      ],
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        [
          "chess",
          "chess"
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          "opening",
          "opening"
        ]
      ]
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  ],
  "synonyms": [
    {
      "word": "Russian Game"
    },
    {
      "word": "Petrov's Defence"
    },
    {
      "word": "Petrov's Defense"
    },
    {
      "word": "Petrov Defense"
    }
  ],
  "word": "Petrov Defence"
}