first class adjective 6noun 3forms 1 adjective6 •Belonging to the best or top group in a system of classification.That was a first class restaurant. •Of, or relating to the most luxurious and expensive class of accommodation on a train, ship, hotel, etc.We travelled first class to New York. •Of, or relating to a class of mail to be delivered before second class.First class stamps are now more expensive. •Of or relating to a first class match. •(UK, India) Great, very enjoyable.- How was your holiday? - It was first class. •Of or relating to a treatment like that for a first-class object.Java has no first-class functions, so function objects are usually expressed by an interface with a single method. noun3 •premier rank.sat in first class; attained first class in the Boy Scouts •(Ireland) The third year of primary school, following after the junior and senior infant levels. •(US) One of two classes of city government in the U.S. state of Kentucky, in which cities elect a mayor and aldermen. formsfirst classes