Definition of: insect

(in′sekt) noun
1. A minute invertebrate animal; one of the class Insecta. The true insects or hexapods have the body divided into a head, a thorax of 3 segments, each of which bears a pair of legs, and an abdomen of 7 to 11 segments, and in development usually pass through a metamorphosis. There are usually 2 pairs of wings, sometimes one pair or none.
2. Loosely, any small, air–breathing invertebrate resembling or suggesting an insect, as spiders, centipedes, ticks, etc. See illustrations of INSECTS (injurious, beneficial) on pages 656 and 657. [<L (animal) insectum (animal) notched or cut into <insectus, pp. of insecare cut into, notch]
—in·sec′te·an (-sek′tē·ən) adjective
—in′sect·like′ adjective