first class

[first class] {n.} 1. The first rank; the highest class; the bestgroup.

The pianist was quite good but he was not in the firstclass.

2. The most expensive or comfortable class of travel; the bestor one of the best groups in which to travel, especially by ship,train, or airplane.

Most people can't afford the first class whenthey take a long journey by ship.

3. The way of sending all mail thatincludes letters and post cards, anything written by hand ortypewriter, and anything sealed so that it cannot be inspected, andthat is the most expensive class of mail but receives the besttreatment.

The usual way to send a letter is by first class.