what is Ki in japnese

Ki is a Japanese word which is written with a Chinese character so there is a Chinese meaning and a Japanese meaning of the word Ki which are very different which creates much confusion. Of course for the Chinese meaning -I suppose that the Chinese pronounce it as Qi or something like that-you better ask the Chinese people, but since I am Japanese I prefer to use the word Ki in the Japanese way. So in the Japanese meaning Ki is something which is unclear, something that cannot be defined