"Black Russia" meaning in English

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  "head_templates": [
    {
      "args": {
        "head": "Black Russia"
      },
      "expansion": "Black Russia",
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  "lang": "English",
  "lang_code": "en",
  "pos": "name",
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          "source": "w"
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          "source": "w"
        },
        {
          "kind": "place",
          "langcode": "en",
          "name": "Historical polities",
          "orig": "en:Historical polities",
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      "derived": [
        {
          "word": "Black Russian"
        }
      ],
      "glosses": [
        "A former principality in Eastern Europe."
      ],
      "id": "en-Black_Russia-en-name-Oe0yHuU4",
      "links": [
        [
          "principality",
          "principality"
        ],
        [
          "Eastern Europe",
          "Eastern Europe#English"
        ]
      ],
      "related": [
        {
          "word": "Blue Russia"
        },
        {
          "word": "Great Russia"
        },
        {
          "word": "Little Russia"
        },
        {
          "word": "New Russia"
        },
        {
          "word": "Russia"
        },
        {
          "word": "White Russia"
        }
      ],
      "synonyms": [
        {
          "word": "Black Ruthenia"
        }
      ]
    }
  ],
  "word": "Black Russia"
}

{
  "derived": [
    {
      "word": "Black Russian"
    }
  ],
  "head_templates": [
    {
      "args": {
        "head": "Black Russia"
      },
      "expansion": "Black Russia",
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  "lang_code": "en",
  "pos": "name",
  "related": [
    {
      "word": "Blue Russia"
    },
    {
      "word": "Great Russia"
    },
    {
      "word": "Little Russia"
    },
    {
      "word": "New Russia"
    },
    {
      "word": "Russia"
    },
    {
      "word": "White Russia"
    }
  ],
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      "glosses": [
        "A former principality in Eastern Europe."
      ],
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          "principality"
        ],
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          "Eastern Europe",
          "Eastern Europe#English"
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      ],
      "synonyms": [
        {
          "word": "Black Ruthenia"
        }
      ]
    }
  ],
  "word": "Black Russia"
}