first-class Definition

1. Referring to the best or highest grade in terms of value, performance or quality.

Thesaurus: excellent, superior, supreme, choice, top drawer, grade A.
2. Excellent.
3. Referring to the most comfortable grade of accommodation in a train, plane, etc.

Example: He took a first-class ticket from Edinburgh to Aberdeen
(chiefly Brit)
4. The category of mail most speedily delivered. Also as noun.

1. By first-class mail, transport, etc

Example: to send it first class
Example: to travel first class
Form: first class