first class • n. a set of people or things grouped together as the best. ∎ the best accommodations in a plane, train, or ship: a seat in first class. ∎ Brit. the highest division in the results of the examinations for a university degree. ∎ the highest division in such an examination: in the college examination he was placed in the first class.• adj. & adv. of the best quality: [as adj.] a full-scale grand opera needs a first-class orchestra. ∎ of or relating to the best accommodations in a train, ship, or plane: [as adj.] first-class air transportation [as adv.] you can travel first class on any train. ∎ of or relating to a class of mail given priority: [as adj.] first-class mail [as adv.] send it first class. ∎ [as adj.] Brit. of or relating to the highest division in a university examination: a first-class honors degree.