hornet
n. countablen. a large type of wasp that can sting. They are often black and yellow or orange and are known for being more aggressive than smaller wasps.
n. a large, stinging social insect belonging to the genus Vespa, within the wasp family Vespidae. Distinguished from other wasps by the larger vertex of the head and the rounded segment of the abdomen.
A hornet flew into the kitchen through the open window.
The gardener warned us to stay away from the old oak tree because a hornet nest was hidden in the hollow trunk.
While a single hornet sting is rarely fatal to humans, the insect's ability to mobilize the entire colony through pheromones makes an disturbed nest a significant safety hazard.
From Middle English hernet, from Old English hyrnetu, hyrnete, from Proto-West Germanic hurnutu, from Proto-Germanic hurznutō (compare German Hornisse), alteration of Proto-Germanic hursulǭ (compare Dutch horzel), from Proto-Indo-European ḱr̥h₂sro- (“hornet”, literally “the one with horns (antennae)”), from ḱerh₂- (“horn”) (compare Welsh creyryn (“gadfly”), Latin crābrō (“hornet”), Lithuanian širšė (“wasp”), Proto-Slavic sьrxy (whence Old Church Slavonic сръшень (srŭšenĭ, “hornet”) and many others), Albanian grerë, grenzë (“wasp, hornet”)).
The collective noun for a group is a 'nest' or 'swarm' of hornets.