斬る[kiru] to kill (a human) using a blade (sword, machete, knife, etc.)
斬新[zanshin] novel
人斬り[hitokiri] assassination
斬刻む[kirikizamu] to hew
斬り込む[kirikomu] to cut into

斬り殺す[kirikorosu] to slay
斬り散らす[kirichirasu] to cut down all
斬り死に[kirijini] fighting to the death (with swords)
斬り倒す[kiritaosu] to cut down
斬り破る[kiriyaburu] to cut to pieces

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