Shippai

shippai: (1) mistake (2) failure

失敗 -- n., adj.

Quote: the famous quote on Doctor-X dorama was "Watashi.. shippai shinai no de!" by Daimon-sensei. And actually that was how I remember the word shippai :D

Shinu

shinu: die

死ぬ -- v.

Transformation:
shinimasu -- v-masu
shinde -- v-te