1. the best, finest, or highest class, grade, or rank.
2. the most expensive and most luxurious class of accommodation on trains, ships, airplanes, etc.
3. (in the U.S. Postal Service) the class of mail consisting of letters, postal cards, or the like, together with all mailable matter sealed against inspection.
4. Brit. Univ.the group receiving the highest distinction in an honors course.
Pronunciation: (fûrst'klas', -kläs'),[key] —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. by first-class conveyance: to travel first-class.