Vajra is a Sanskrit word meaning both thunderbolt and diamond. Additionally, it is a weapon won in battle which is used as a ritual object to symbolize both the properties of a diamond (indestructibility) and a thunderbolt (irresistible force).
The vajra is essentially a type of club with a ribbed spherical head. The ribs may meet in a ball-shaped top, or they may be separate and end in sharp points with which to stab. The vajra is the weapon of the Vedic rain and thunder-deity Indra, and is used symbolically by the dharma traditions of Buddhism, Jainism and Hinduism, often to represent firmness of spirit and spiritual power.