This Japanese compound kotodama combines koto 言 "word; speech" and tama 霊 "spirit; soul" (or 魂 "soul; spirit; ghost") voiced as dama in rendaku. In contrast, the unvoiced kototama pronunciation especially refers to kototamagaku (言霊学, "study of kotodama"), which was popularized by Onisaburo Deguchi in the Oomoto religion. This field takes the Japanese gojūon phonology as the mystical basis of words and meanings, in rough analogy to Hebrew Kabbalah.
The etymology of kotodama is uncertain, but one explanation correlating words and events links two Japanese words pronounced koto: this 言 "word; words; speech" and 事 "situation; circumstances; state of affairs; occurrence; event; incident". These two kanji were used interchangeably in the name Kotoshironushi 事代主 or 言代主, an oracular kami mentioned in the Kojiki and Nihon shoki. Kotodama is related with Japanese words such as kotoage 言挙 "words raised up; invoke the magical power of words", kotomuke 言向 "directed words; cause submission though the power of words", and jumon 呪文 "magic spell; magic words; incantation".
Kotodama is a central concept in Japanese mythology, Shinto, and Kokugaku. For example, the Kojiki describes an ukei (or seiyaku) 誓約 "covenant; trial by pledge" between the sibling gods Susanoo and Amaterasu, "Let each of us swear, and produce children". Uttering the divine words of the Shinto divination ritual known as ukehi supposedly determines results, and in this case, Amaterasu giving birth to five male deities proved that Susanoo's intentions were pure.
Kototama or kotodama is also fundamental to Japanese martial arts, for instance, in the use of kiai. Morihei Ueshiba, the founder of aikido and a student of Deguchi, used kototama as a spiritual basis for his teachings. William Gleason says Ueshiba "created aikido based on the kototama principle," and quotes him that "Aikido is the superlative way to practice the kototama. It is the means by which one realizes his true nature as a god and finds ultimate freedom." Mutsuro Nakazono, a disciple of Ueshiba, wrote books on the importance of kototama in aikido, such as The Kotoma Principle in 1983.
While other cultures have parallels to kotodama, such as mantra, mana, and logos, some Japanese people believe the "word spirit" is unique to the Japanese language. One of the classical names of Japan is kototama no sakiwau kuni (言霊の幸わう国, "the land where the mysterious workings of language bring bliss"), a phrase that originated in the Man'yōshū.