Noun | 1. | ![]() animal order - the order of animals class Hexapoda, class Insecta, Hexapoda, Insecta - insects; about five-sixths of all known animal species louse, sucking louse - wingless usually flattened bloodsucking insect parasitic on warm-blooded animals family Pediculidae, Pediculidae - true lice: human lice and related forms family Phthiriidae, Phthiriidae - crab lice |