a member of the class Insecta (phylum Arthropoda), characterized (as adults) by a body segmented into three distinct regions (head, thorax, abdomen), by a head with one pair of antennae, by a thorax with three (often nondistinct) segments each with a pair of legs, and usually one or two pairs of thoracic wings —note not all insects are winged: some (primitive) insects have never developed wings, some have vestigial wings, and some have evolved from winged ancestors into present wingless forms This definition last updated 10/28/2008