"line to gain" meaning in English

{
  "head_templates": [
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        "1": "?"
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      "expansion": "line to gain",
      "name": "en-noun"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
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          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
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          "source": "w"
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        {
          "kind": "topical",
          "langcode": "en",
          "name": "Football (American)",
          "orig": "en:Football (American)",
          "parents": [
            "Football",
            "Ball games",
            "Sports",
            "Human activity",
            "Human behaviour",
            "Human",
            "All topics",
            "Fundamental"
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          "source": "w"
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      ],
      "glosses": [
        "The points on the football field needed to pass to convert a first down."
      ],
      "id": "en-line_to_gain-en-noun-A9jpEcOB",
      "links": [
        [
          "American football",
          "American football"
        ],
        [
          "first down",
          "first down"
        ]
      ],
      "raw_glosses": [
        "(American football) The points on the football field needed to pass to convert a first down."
      ],
      "topics": [
        "American-football",
        "ball-games",
        "football",
        "games",
        "hobbies",
        "lifestyle",
        "sports"
      ]
    }
  ],
  "word": "line to gain"
}

{
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      "args": {
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      "expansion": "line to gain",
      "name": "en-noun"
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  "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",
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        "en:Football (American)"
      ],
      "glosses": [
        "The points on the football field needed to pass to convert a first down."
      ],
      "links": [
        [
          "American football",
          "American football"
        ],
        [
          "first down",
          "first down"
        ]
      ],
      "raw_glosses": [
        "(American football) The points on the football field needed to pass to convert a first down."
      ],
      "topics": [
        "American-football",
        "ball-games",
        "football",
        "games",
        "hobbies",
        "lifestyle",
        "sports"
      ]
    }
  ],
  "word": "line to gain"
}