"back rank" meaning in English

{
  "forms": [
    {
      "form": "back ranks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "back rank (plural back ranks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Entries with translation boxes",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Finnish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with German translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Polish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Chess",
          "orig": "en:Chess",
          "parents": [],
          "source": "w"
        }
      ],
      "derived": [
        {
          "word": "back-rank mate"
        }
      ],
      "glosses": [
        "The row on the board on which the pieces (e.g. king, queen) start."
      ],
      "id": "en-back_rank-en-noun-Zyth3ESA",
      "links": [
        [
          "chess",
          "chess"
        ],
        [
          "row",
          "row"
        ],
        [
          "board",
          "board"
        ],
        [
          "piece",
          "piece"
        ],
        [
          "king",
          "king"
        ],
        [
          "queen",
          "queen"
        ]
      ],
      "raw_glosses": [
        "(chess) The row on the board on which the pieces (e.g. king, queen) start."
      ],
      "topics": [
        "board-games",
        "chess",
        "games"
      ],
      "translations": [
        {
          "code": "fi",
          "lang": "Finnish",
          "lang_code": "fi",
          "sense": "Translations",
          "word": "perärivi"
        },
        {
          "code": "de",
          "lang": "German",
          "lang_code": "de",
          "sense": "Translations",
          "tags": [
            "feminine"
          ],
          "word": "Grundreihe"
        },
        {
          "code": "pl",
          "lang": "Polish",
          "lang_code": "pl",
          "sense": "Translations",
          "tags": [
            "masculine"
          ],
          "word": "mat korytarzowy"
        }
      ]
    }
  ],
  "word": "back rank"
}

{
  "derived": [
    {
      "word": "back-rank mate"
    }
  ],
  "forms": [
    {
      "form": "back ranks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "back rank (plural back ranks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Entries with translation boxes",
        "Pages with 1 entry",
        "Pages with entries",
        "Terms with Finnish translations",
        "Terms with German translations",
        "Terms with Polish translations",
        "Translation table header lacks gloss",
        "en:Chess"
      ],
      "glosses": [
        "The row on the board on which the pieces (e.g. king, queen) start."
      ],
      "links": [
        [
          "chess",
          "chess"
        ],
        [
          "row",
          "row"
        ],
        [
          "board",
          "board"
        ],
        [
          "piece",
          "piece"
        ],
        [
          "king",
          "king"
        ],
        [
          "queen",
          "queen"
        ]
      ],
      "raw_glosses": [
        "(chess) The row on the board on which the pieces (e.g. king, queen) start."
      ],
      "topics": [
        "board-games",
        "chess",
        "games"
      ]
    }
  ],
  "translations": [
    {
      "code": "fi",
      "lang": "Finnish",
      "lang_code": "fi",
      "sense": "Translations",
      "word": "perärivi"
    },
    {
      "code": "de",
      "lang": "German",
      "lang_code": "de",
      "sense": "Translations",
      "tags": [
        "feminine"
      ],
      "word": "Grundreihe"
    },
    {
      "code": "pl",
      "lang": "Polish",
      "lang_code": "pl",
      "sense": "Translations",
      "tags": [
        "masculine"
      ],
      "word": "mat korytarzowy"
    }
  ],
  "word": "back rank"
}