First class and Jouncy

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

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

Jouncy adjective - Marked by a series of sharp quick motions.

First class and jouncy are semantically related. Sometimes you can use "First class" instead an adjective "Jouncy".