We love words that sound like what they mean, and bolt is no exception. It's a quick, sharp word that either means to move quickly or refers to a stroke of lightning, as in "lightning bolt."
The god Zeus was fond of tossing bolts of lightning down upon mortals who angered him. If you were one of those mortals, you'd have been smart to bolt inside as soon as the rain began. To bolt is to run as quickly as you can. Racehorses are often described as bolting out of the gate. Other uses of bolt include the lock in your door, the act of locking that lock, and what a dog does when it gulps down his food.