Definition of first classes:
(adj) :
Belonging to the best or top group in a system of classification.
(adj) :
Of, or relating to the most luxurious and expensive class of accommodation on a train, ship, hotel, etc.
(adj) :
Of, or relating to a class of mail to be delivered before second class.
(n) :
(A status, section, etc which is of) premier rank.
(adj) :
(UK, India) Great, very enjoyable.
(adj) :
(cricket) Of or relating to a first class match.