Kotodama (言霊) refers to the belief that words have mystical powers. It combines the word for "speech" (言 koto) and the word for "soul"(霊 tama).

Kotodama presupposes that sounds can magically affect objects and that the ritualistic chanting of words can affect both the individual and her environment. For example, if you call out someone's name, the sound will have an impact on them, whether they can hear you or not.

Kotodama has its roots in Shinto, Japan's animistic religion. In ancient times, spells and incantations to the Shinto gods were seen as having divine power. Shintoists believe that not only people but also animals and objects have souls, so it is not surprising that they believe that words have souls too.

Kotodama is not as foreign a concept as it might at first appear. Though outdated, the belief in magical words, be it hocus pocus, abracadabra or open sesame, was once widespread. In Hinduism, it is believed that different words produce different vibrations and that chanting them as mantras will create different effects, be it inner peace, the healing of injuries, or protection from bad luck. Hindu mantras usually start with the word "Om," which is believed to be the sound of the universe.

In Japan, belief in kotodama is as old as the written word. In the Man'yoshu, the oldest surviving collection of Japanese waka poetry, which was compiled sometimes after AD 759, Japan is referred to as kotodama no sakiwau kuni (言霊の幸わう国), or "the land where the mysterious workings of language bring bliss."

Originally, only Shintoist spells and incantations were seen as having divine power, but in time, other words came to be regarded as divine too. One example to have survived to the present day is the short shout uttered when making an attacking move in karate or aikido. It is called kiai (気合) and is supposed to concentrate the attacker's resolve.