殫精極慮 [ㄉㄢ ㄐㄧㄥ ㄐㄧˊ ㄌㄩˋ; dan1 jing1 ji2 lu:4] to exhaust one's thoughts and ingenuity (idiom); to think sth through thoroughly to rack one's brains to leave no stone unturned ◄ ►