first class -- (the most expensive accommodations on a ship or train or plane)
Overview of adj first-class
The adj first-class has 1 sense
excellent, first-class, fantabulous, splendid -- (very good;of the highest quality; "made an excellent speech"; "the school has excellent teachers"; "a first-class mind")
Overview of adv first-class
The adv first class has 1 sense
first class -- (by first class conveyance; with first class accommodations; "we always travel first class")