A Sanskrit word that means both diamond (which can cut anything without itself being cut) and thunderbolt (meaning irresistible force). Symbolically, it represents spiritual power and the firmness of spirit. In Tantric Buddhism it is represented in ritual by a device that looks like a fist at the end of a short arm, often just two connected fists. Thus it is sometimes a term for the male sexual organ also meaning a scepter of power. It is a symbol of one of the three major branches of Buddhism.