The Collaborative International Dictionary of English v.0.48:

First-class \First"-class`\, a.
   Of the best class; of the highest rank; in the first
   division; of the best quality; first-rate; as, a first-class
   telescope.
   [1913 Webster]

   First-class car or First-class railway carriage, any
      passenger car of the highest regular class, and intended
      for passengers who pay the highest regular rate; --
      distinguished from a second-class car.
      [1913 Webster]