"fastback" meaning in English

{
  "forms": [
    {
      "form": "fastbacks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "fastback (plural fastbacks)",
      "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"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Automotive",
          "orig": "en:Automotive",
          "parents": [
            "Transport",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "coordinate_terms": [
        {
          "word": "hatchback"
        },
        {
          "word": "notchback"
        }
      ],
      "glosses": [
        "A motor car having a continuous slope from the roof to the rear"
      ],
      "id": "en-fastback-en-noun-fUDsuXmD",
      "links": [
        [
          "motor car",
          "motor car"
        ],
        [
          "slope",
          "slope"
        ]
      ]
    }
  ],
  "word": "fastback"
}

{
  "coordinate_terms": [
    {
      "word": "hatchback"
    },
    {
      "word": "notchback"
    }
  ],
  "forms": [
    {
      "form": "fastbacks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "fastback (plural fastbacks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Automotive"
      ],
      "glosses": [
        "A motor car having a continuous slope from the roof to the rear"
      ],
      "links": [
        [
          "motor car",
          "motor car"
        ],
        [
          "slope",
          "slope"
        ]
      ]
    }
  ],
  "word": "fastback"
}

{
  "called_from": "linkages/371",
  "msg": "unrecognized linkage prefix: (motorcar): hatchback, notchback desc=motorcar rest=hatchback, notchback cls=romanization cls2=romanization e1=True e2=False",
  "path": [
    "fastback"
  ],
  "section": "English",
  "subsection": "noun",
  "title": "fastback",
  "trace": ""
}