Once in a year, the 45′ tall statue of Lord Jagannath will be taken in a procession through the streets of Puri. The rath/ chariot was pulled by thousands of devotees. Anything that came under the wheels would get crushed.
The word Juggernaut is the Anglicized version of Jagannath. It has come to denote a relentless and unstoppable force that would crush anything in its path.
Recently the word has been applied to the giant trucks on the modern roads.
