ミドル級[midorukyuu] middleweight class
一級[ikkyuu] one grade
下級[kakyuu] lower grade
下級職[kakyuushoku] subordinate post
下級審[kakyuushin] lower court

下級生[kakyuusei] underclassmen
下層階級[kasoukaikyuu] proletariat
仮進級[karishinkyuu] conditional promotion
階級[kaikyuu] (social) class
階級章[kaikyuushou] rank insignia

乗羃[joubeki] power
羃集合[bekishuugou] power set

羃級数[bekikyuusuu] power series