a) An arthropod in the class Insecta, characterized by six legs, up to four wings, and a chitinous exoskeleton.
Our shed has several insect infestions, including ants, yellowjackets, and wasps.
b) Any small arthropod similar to an insect including spiders, centipedes, millipedes, etc
The swamp is swarming with every sort of insect.
Wikipedia foundation.