/ferrst"klas", -klahs"/ , adj.
1. of the highest or best class or quality: a first-class movie.
2. best-equipped and most expensive: a first-class railroad car.
3. given or entitled to preferred treatment, handling, etc.: first-class mail.
adv.
4. by first-class conveyance: to travel first-class.
[ 1780-90 ]