thunderstone

or thun·der-stone

[ thuhn-der-stohn ]
/ ˈθʌn dərˌstoʊn /

noun

any of various stones or fossils formerly thought to be fallen thunderbolts.
Archaic. a thunderbolt or flash of lightning.

Example sentences from the Web for thunderstone

British Dictionary definitions for thunderstone

thunderstone
/ (ˈθʌndəˌstəʊn) /

noun

a long tapering stone, fossil, or similar object, formerly thought to be a thunderbolt
an archaic word for thunderbolt