noun , adverb
■ noun [ U ]
1.
the best and most expensive seats or accommodation on a train, plane or ship :
There is more room in first class.
2.
(in Britain) the class of mail that is delivered most quickly :
First class costs more.
3.
(in the US) the class of mail that is used for letters
4.
the highest standard of degree given by a British university
■ adverb
1.
using the best and most expensive seats or accommodation in a train, plane or ship :
to travel first class
2.
(in Britain) by the quickest form of mail :
I sent the package first class on Monday.
3.
(in the US) by the class of mail that is used for letters