Noun | 1. | ![]() animal order - the order of animals class Hexapoda, class Insecta, Hexapoda, Insecta - insects; about five-sixths of all known animal species collembolan, springtail - any of numerous minute wingless primitive insects possessing a special abdominal appendage that allows the characteristic nearly perpetual springing pattern; found in soil rich in organic debris or on the surface of snow or water |