one of the insecta; esp., one of the hexapoda. see insecta.-any air-breathing arthropod, as a spider or scorpion.-any small crustacean. in a wider sense, the word is often loosely applied to various small invertebrates.-fig.: any small, trivial, or contemptible person or thing.-of or pertaining to an insect or insects.-like an insect; small; mean; ephemeral.