Noun has 3 senses

• first class(n = noun.attribute) - the highest rank in a classification;


• first class(n = noun.communication) 1st class, 1st-class mail, first-class mail - mail that includes letters and postcards and packages sealed against inspection;



• first class(n = noun.artifact) - the most expensive accommodations on a ship or train or plane;

Adverbial has 1 sense

• first class(r = adv.all) - by first class conveyance; with first class accommodations; "we always travel first class"