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

一首[isshu] tanka
鎌首[kamakubi] sickle-shaped neck (e.g. snake, praying mantis)
丸首[marukubi] round-necked (T-shirt)
偽首[nisekubi] falsified severed head
カリ首[karikubi] (something resembling a) goose's neck

がん首[gankubi] head of a pipe, incl. the bowl and stem attachment
機首[kishu] nose (of plane)
襟首[erikubi] nape of neck
元首[genshu] ruler
絞首刑[koushukei] death by hanging