The word Reiki is composed of two Japanese words - Rei and Ki. When translating Japanese into English we must keep in mind that an exact translation is difficult. The Japanese language has many levels of meaning. Therefore the context the word is being used in must be kept in mind when attempting to communicate its essence. Because these words are used in a spiritual healing context, a Japanese/English dictionary does not provide the depth of meaning we seek, as its definitions are based on common everyday Japanese. As an example, Rei is often defined as ghost and Ki as vapor and while these words vaguely point in the direction of meaning we seek.
With the above information in mind, Reiki can be defined as a non-physical healing energy made up of life force energy that is guided by the Higher Intelligence, or spiritually guided life force energy. This is a functional definition as it closely parallels the experience of those who practice Reiki in that Reiki energy seems to have an intelligence of its own flowing where it is needed in the client and creating the healing conditions necessary for the individuals needs. It cannot be guided by the mind, therefore it is not limited by the experience or ability of the practitioner. Nether can it be misused as it always creates a healing effect. It must be kept in mind that Reiki is not the same as simple life force energy as life force energy by itself can be influenced by the mind and because of this, can create benefit as well as cause problems including ill health.