"flatted fifth" meaning in English

{
  "forms": [
    {
      "form": "flatted fifths",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "flatted fifth (plural flatted fifths)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2011, Mark Phillips, Jon Chappell, Guitar For Dummies, John Wiley & Sons, page 192",
          "text": "A flatted fifth is a note that's a half step (or one fret) lower than the regular fifth of a scale.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Synonym of diminished fifth"
      ],
      "id": "en-flatted_fifth-en-noun-Vu6C3te3",
      "links": [
        [
          "diminished fifth",
          "diminished fifth#English"
        ]
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "diminished fifth"
        }
      ]
    }
  ],
  "word": "flatted fifth"
}

{
  "forms": [
    {
      "form": "flatted fifths",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "flatted fifth (plural flatted fifths)",
      "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",
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "2011, Mark Phillips, Jon Chappell, Guitar For Dummies, John Wiley & Sons, page 192",
          "text": "A flatted fifth is a note that's a half step (or one fret) lower than the regular fifth of a scale.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Synonym of diminished fifth"
      ],
      "links": [
        [
          "diminished fifth",
          "diminished fifth#English"
        ]
      ],
      "synonyms": [
        {
          "tags": [
            "synonym",
            "synonym-of"
          ],
          "word": "diminished fifth"
        }
      ]
    }
  ],
  "word": "flatted fifth"
}