3. Vehement threatening or censure; especially, ecclesiastical denunciation; fulmination. He severely threatens such with the thunderbolt of excommunication. (Hakewill)
(Science: zoology) Thunderbolt beetle, a long-horned beetle (Arhopalus fulminans) whose larva bores in the trunk of oak and chestnut trees. It is brownish and bluish-black, with W-shaped whitish or silvery markings on the elytra.