| Noun | 1. | Plecoptera - stoneflies animal order - the order of animals class Hexapoda, class Insecta, Hexapoda, Insecta - insects; about five-sixths of all known animal species plecopteran, stone fly, stonefly - primitive winged insect with a flattened body; used as bait by fishermen; aquatic gilled larvae are carnivorous and live beneath stones |