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

一念発起[ichinenhokki] being resolved to (do something)
引き起す[hikiokosu] to cause
縁起[engi] omen
喚起[kanki] arousal
起きる[okiru] to get up

起上る[okiagaru] to rise
起す[okosu] to raise
起こり得る[okoriuru] to be possible to occur
起る[okoru] to occur
起つ[tatsu] to rise up