First class and Optimal

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

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

Optimal adjective - Most desirable possible under a restriction expressed or implied.

First class and optimal are semantically related. Sometimes you can use "First class" instead an adjective "Optimal".

Nearby Words: optimum, optimization, optimize, optimise, optimally