"crack train" meaning in English

{
  "antonyms": [
    {
      "word": "local train"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "crack",
        "3": "",
        "4": "best, first-rate"
      },
      "expansion": "crack (“best, first-rate”)",
      "name": "m"
    }
  ],
  "etymology_text": "From crack (“best, first-rate”).",
  "forms": [
    {
      "form": "crack trains",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "crack train (plural crack trains)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "1988 Lawrence Davis, Pullman porter in the 1940s, quoted on Different Trains, by Steve Reich.\nThe crack train from New York."
        }
      ],
      "glosses": [
        "Fastest express train between two stops."
      ],
      "id": "en-crack_train-en-noun-s8zbMEHI",
      "links": [
        [
          "express train",
          "express train"
        ]
      ],
      "raw_glosses": [
        "(US, dialect, dated) Fastest express train between two stops."
      ],
      "synonyms": [
        {
          "word": "express train"
        },
        {
          "word": "fast train"
        }
      ],
      "tags": [
        "US",
        "dated",
        "dialectal"
      ]
    }
  ],
  "word": "crack train"
}

{
  "antonyms": [
    {
      "word": "local train"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "crack",
        "3": "",
        "4": "best, first-rate"
      },
      "expansion": "crack (“best, first-rate”)",
      "name": "m"
    }
  ],
  "etymology_text": "From crack (“best, first-rate”).",
  "forms": [
    {
      "form": "crack trains",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "crack train (plural crack trains)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "American English",
        "English countable nouns",
        "English dated terms",
        "English dialectal terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns"
      ],
      "examples": [
        {
          "text": "1988 Lawrence Davis, Pullman porter in the 1940s, quoted on Different Trains, by Steve Reich.\nThe crack train from New York."
        }
      ],
      "glosses": [
        "Fastest express train between two stops."
      ],
      "links": [
        [
          "express train",
          "express train"
        ]
      ],
      "raw_glosses": [
        "(US, dialect, dated) Fastest express train between two stops."
      ],
      "tags": [
        "US",
        "dated",
        "dialectal"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "express train"
    },
    {
      "word": "fast train"
    }
  ],
  "word": "crack train"
}