ご多忙中[gotabouchuu] in the midst of your work (often used as a formal phrase in business letters, etc.)
多忙[tabou] busy
忙がしい[sewashii] busy
繁忙[hanbou] pressure of business
忙殺[bousatsu] being extremely busy

忙しげ[sewashige] looking busy
気忙しい[kizewashii] restless
忙中[bouchuu] (in the midst of) busyness
心忙しい[kokorozewashii] restless
仕事で忙しい[shigotodeisogashii] busy with one's work

ブチ殺す[buchikorosu] to kill by hitting
押殺す[oshikorosu] to crush to death
あっ殺[assatsu] crushing to death
暗殺[ansatsu] assassination
暗殺事件[ansatsujiken] assassination

一殺那[issetsuna] (a) moment
殴り殺す[nagurikorosu] to strike dead
殴殺[ousatsu] beating to death
皆殺し[minagoroshi] massacre
かみ殺す[kamikorosu] to stifle a smile, yawn, etc.