A large, eusocial wasp (family Vespidae), resembling a common wasp but some up to 5.5 cm long, that builds papery nests, each with one queen attended by workers. Hornets will defend their nests aggressively, their stings are more severe than those of smaller wasps, and a hornet can sting repeatedly. There are about 25 species, all in the genus Vespa, found throughout most of the northern hemisphere.