(Zool.) One of the classes of Arthropoda, including those that have one pair of antennae, three pairs of mouth organs, and breathe air by means of tracheae, opening by spiracles along the sides of the body. In this sense it includes the Hexapoda, or six-legged insects and the Myriapoda, with numerous legs. See Insect, n.
(Zool.) In a more restricted sense, the Hexapoda alone. See Hexapoda.
(Zool.) In the most general sense, the Hexapoda, Myriapoda, and Arachnoidea, combined. Note: The typical Insecta, or hexapod insects, are divided into several orders, viz.: Hymenoptera, as the bees and ants; Diptera, as the common flies, gnats, and mosquitos; Aphaniptera, or fleas; Lepidoptera, or moths and butterflies; Neuroptera, as the ant-lions and hellgamite; Coleoptera, or beetles; Hemiptera, as bugs, lice, aphids; Orthoptera, as grasshoppers and cockroaches; Pseudoneuroptera, as the dragon flies and termites; Euplexoptera, or earwigs; Thysanura, as the springtails, podura, and lepisma. See these words in the Vocabulary.