Wiktionary
n. (context obsolete English) A cannonball.
Wikipedia
Gunstone is a hamlet in the South Staffordshire district of Staffordshire, England. It is situated north east of the village of Codsall.
Usage examples of "gunstone".
Prince this mock of his hath turned his balls to gunstones, and his soul shall stand sore charged for the wasteful vengeance that shall fly with them.
Let me use my magic for more than changing stones to enchanted silver, and I will conjure a hundred ensorceled gunstones, more powerful than the one your foe used to stun the dragon turtle.
There were even guns among them with no locks at all that were fired by jamming a cigarillo against the vent in the barrel, sending the gunstones from the riverbed with which they were loaded whissing through the air on flights of their own eccentric selection like the paths of meteorites.