Reiki is commonly written as 霊気.
It compounds the words rei (霊: "spirit, miraculous, divine") and ki (気; qi: "gas, vital energy, breath of life, consciousness").
The Japanese kan (館, kan) means "house" or "hall".
Originally, Reiki was written as 靈氣. It derives from the Chinese loanword língqì
(靈氣, "supernatural influence").