Condign and First class

Condign adjective - Being what is called for by accepted standards of right and wrong.

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

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

Condign and first class are semantically related. Sometimes you can use "Condign" instead an adjective phrase "First class".