A thunderbolt or lightning bolt is a symbolic representation of lightning when accompanied by a loud thunderclap. In ancient Hellenic and Roman religious traditions, the thunderbolt represents Zeus or Jupiter (etymologically 'Sky Father'), thence the origin and ordaining pattern of the universe, as expressed in Heraclitus' fragment describing "the Thunderbolt that steers the course of all things". It is the same in other Indo-European traditions, for example the Vedic Vajra.
In its original usage the word may also have been a description of the consequences of a close approach between two planetary cosmic bodies, as Plato suggested in Timaeus, or, according to Victor Clube, meteors, though this is not currently the case. As a divine manifestation the thunderbolt has been a powerful symbol throughout history, and has appeared in many mythologies. Drawing from this powerful association, the thunderbolt is often found in military symbolism and semiotic representations of electricity.