"eight-bar blues" meaning in English

{
  "forms": [
    {
      "form": "eight-bar blues",
      "tags": [
        "plural"
      ]
    }
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        "1": "~",
        "2": "eight-bar blues"
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      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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        {
          "kind": "topical",
          "langcode": "en",
          "name": "Blues music",
          "orig": "en:Blues music",
          "parents": [
            "Musical genres",
            "Genres",
            "Music",
            "Entertainment",
            "Art",
            "Sound",
            "Culture",
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            "Society",
            "Nature",
            "All topics",
            "Fundamental"
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          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Eight",
          "orig": "en:Eight",
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            "Fundamental"
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          "name": "Music",
          "orig": "en:Music",
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            "Sound",
            "Culture",
            "Energy",
            "Society",
            "Nature",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A blues form built on an eight-measure chord pattern, most typically I, I, IV, I, V7, IV, I, V7, where I, IV and V7 represent the tonic, subdominant and dominant seventh chords respectively."
      ],
      "id": "en-eight-bar_blues-en-noun-FMwd1h5v",
      "links": [
        [
          "music",
          "music"
        ],
        [
          "blues",
          "blues"
        ],
        [
          "tonic",
          "tonic"
        ],
        [
          "subdominant",
          "subdominant"
        ],
        [
          "dominant seventh",
          "dominant seventh"
        ]
      ],
      "raw_glosses": [
        "(music) A blues form built on an eight-measure chord pattern, most typically I, I, IV, I, V7, IV, I, V7, where I, IV and V7 represent the tonic, subdominant and dominant seventh chords respectively."
      ],
      "related": [
        {
          "word": "blues"
        },
        {
          "word": "turnaround"
        },
        {
          "word": "twelve-bar blues"
        }
      ],
      "tags": [
        "countable",
        "uncountable"
      ],
      "topics": [
        "entertainment",
        "lifestyle",
        "music"
      ]
    }
  ],
  "word": "eight-bar blues"
}

{
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    {
      "form": "eight-bar blues",
      "tags": [
        "plural"
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    }
  ],
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        "2": "eight-bar blues"
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      "expansion": "eight-bar blues (countable and uncountable, plural eight-bar blues)",
      "name": "en-noun"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "blues"
    },
    {
      "word": "turnaround"
    },
    {
      "word": "twelve-bar blues"
    }
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        "English uncountable nouns",
        "en:Blues music",
        "en:Eight",
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      "glosses": [
        "A blues form built on an eight-measure chord pattern, most typically I, I, IV, I, V7, IV, I, V7, where I, IV and V7 represent the tonic, subdominant and dominant seventh chords respectively."
      ],
      "links": [
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          "music",
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        ],
        [
          "blues",
          "blues"
        ],
        [
          "tonic",
          "tonic"
        ],
        [
          "subdominant",
          "subdominant"
        ],
        [
          "dominant seventh",
          "dominant seventh"
        ]
      ],
      "raw_glosses": [
        "(music) A blues form built on an eight-measure chord pattern, most typically I, I, IV, I, V7, IV, I, V7, where I, IV and V7 represent the tonic, subdominant and dominant seventh chords respectively."
      ],
      "tags": [
        "countable",
        "uncountable"
      ],
      "topics": [
        "entertainment",
        "lifestyle",
        "music"
      ]
    }
  ],
  "word": "eight-bar blues"
}