The word 'reiki' is defined as an 'ethereal ki' in the Japanese dictionary.  'Ethereal' in this sense means miraculous and sacred.  Thus 'reiki' is a ki - cosmic energy - with a miraculous and sacred power.

The word 'reiki' is used often by spiritual therapists during Meiji (1868-1912), Taisho (1912-1925) and early Showa (1926-1988) Era.  Many people used the word 'reiki ryoho' to refer to their therapies, and 'reiki ryoho' is not original with Usui Sensei.  The name Usui Sensei used was 'Usui Reiki Ryoho.'

The first person to use the term 'reiki ryoho' was Mataji Kawakami, who was a therapist, who published Reiki Ryoho to sono Koka (Reiki Ryoho and its Effects) in 1919.  However, today the term 'reiki ryoho' almost exclusively refers to Usui Reiki Ryoho.