First and First class

First adjective - Coming before all others in time or order.

First class and first are semantically related In some cases you can use "First class" instead an adjective "First".

Nearby Word: firstly

First class noun - Mail that includes letters and postcards and packages sealed against inspection.

First and first class are semantically related in prime topic. Sometimes you can use "First" instead an adjective phrase "First class", if it concerns topics such as best, top, superior, excellent.